377
REVIEWS / SYNTH~SES
Dolichol: a curriculum cognitionis FRANK W. HEMMING Biochem. Cell Biol. Downloaded from www.nrcresearchpress.com by University of Western Ontario on 11/12/14 For personal use only.
Department of Biochemistry, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, U.K. Received June 27, 1991 HEMMING, F. W. 1992. Dolichol: a curriculum cognitionis. Biochem. Cell Biol. 70: 377-381. Dolichols were first described about 30 years ago when animal tissues were being examined for the presence of a putative precursor to the polyisoprenoid side chain of ubiquinone. These long-chain 2,3-dihydro-polycis-isoprenoid alcohols are found in all eukaryotic organisms. In many plant tissues they are accompanied by families of other polyisoprenoid alcohols that are usually similar molecules and possess an unsaturated a-isoprene residue. Analogy with the role of bactoprenyl phosphates in the synthesis of bacterial wall glycans led to the discovery that the mono- and di-phosphates of dolichols function as cofactors in protein N-glycosylation, involving the formation of glycosylated derivatives of dolichol as intermediates. Variation of the concentration of dolichyl phosphate was shown to be one way of controlling protein N-glycosylation. This can be achieved by modification of the relative activities of dolichol kinase and dolichol phosphate phosphatase. Modulation of the biosynthetic pathway, still not fully understood, of dolichyl phosphate may also be an important factor. Several disease conditions involve aberrations in these pathways. Key words: dolichols, polyisoprenoid alcohols, N-glycosylation, 0-mannosylation. HEMMING, F. W. 1992. Dolichol: a curriculum cognitionis. Biochem. Cell Biol. 70 : 377-381. La premiere description des dolichols remonte A environ 30 ans lors de l'examen de tissus animaux pour la prtsence d'un precurseur possible de la chaine lattrale polyisoprtno'ide de l'ubiquinone. Ces 2,3-dihydro-polycis-isoprtnoide alcools ti longue chaine sont prtsents dans tous les organismes eucaryotes. Dans beaucoup de tissus vegttaux, ils sont accompagnts de familles d'autres alcools polyisoprtnoides qui sont habituellement des moltcules similaires et possedent un rtsidu a-isoprene non sature. L'analogie avec le r61e des bactoprenyl phosphates dans la synthbe des glycanes des parois bacteriennes a permis la dkcouverte que les mono- et les di-phosphates des dolichols agissent comme cofacteurs dans la N-glycosylation des prottines, impliquant la formation de derives glycosyles du dolichol comme intermediaires. Nous montrons que la variation de la concentration du dolichyl phosphate est une voie de contr6le de la N-glycosylation des proteines. Cela peut s'effectuer par modification des activites relatives de la dolichol kinase et de la dolichol phosphate phosphatase. La modulation de la voie biosynthktique, encore ma1 comprise, du dolichyl phosphate peut Ctre egalement un facteur important. Plusieurs conditions pathologiques impliquent des aberrations dans ces voies. Mots clis : dolichols, alcools, polyisoprtnoides, N-glycosylation, 0-mannosylation. [Traduit par la rtdaction]
Although it is likely that dolichols and related compounds have been components of living systems since early in evolution, they have been recognized for only 30 or so years. Dolichol (Fig. 1) was first described in 1960 in a proceedings abstract (Hemming et al. 1960) and in a short paper (Pennock et al. 1960) (Table 1). It was observed as a major component of the unsaponifiable lipid of human kidney during studies on ubiquinone and related components, which had been shown a little time before to have a polyisoprenoid side chain (Fig. 2) (Morton et al. 1958). The polyisoprenoid nature of the alcohol was based primarily on comparisons of infrared spectrum, iodine number, and results of ozonolysis with solanesol, the all-transpolyprenol-9 (Table 2, Rowland et al. 1956) isolated earlier from tobacco leaves. Saturation of the 2,3-double bond was deduced by infrared spectroscopy, ozonolysis, and the ultraviolet absorption spectrum of dolichaldehyde 2,4-dinitrophenylhydrazone.Chain length was estimated by the extent of dilution of the extinction value (E::!,,) of the ultraviolet and visible absorption spectra of chromophoric acids when esterified to dolichol. As in most areas, advances in this field were technology led. The rapidly developing techniques of NMR, mass spectrometry, and thin-layer chromatography (then new!) quickly ABBREVIATION: NMR, nuclear magnetic resonance. Printed in Canada / Imprime au Canada
L
1n-I FIG. 1. Dolichol, n = 11-23.
FIG. 2. Ubiquinone, n = 6-10.
confirmed and extended these early findings. In particular, NMR showed the presence of two internal isoprene residues in the trans configuration, the rest being cis (see Table 2). It is worth noting that in fact the techniques available 30 or 40 years earlier did not allow Channon and Marrian (1926) to recognize the presence of a hydroxyl group in what
BIOCHEM. CELL BIOL. VOL. 70, 1992
378
TABLE1. Curriculum cognitionis Name (alias)
Dolichol (2,3-dihydropolyisoprenoidalcohol,
Biochem. Cell Biol. Downloaded from www.nrcresearchpress.com by University of Western Ontario on 11/12/14 For personal use only.
hepene?) Date of discovery
Pennock et al. 1960; Burgos et al. 1963; Channon and Marrian 1926
Place of discovery
Liverpool, U.K.
Address Place of formation Place of work Also frequents
No fixed abode Rough endoplasmic reticulum Rough endoplasmic reticulum Other membranes (Golgi, plasma membrane) and lysosomes
Characteristic features
Next of kin (close relations)
Work experience Recent areas of special interest
Referees
Hydrophobic alcohol, many isoprene units in the order WT,C,S-OH (n = 9-20) (plus n + 1, n + 2, n + 3 and n + 4); often as monoor di-phosphatea Families of polyprenols (2-ene); rubber, gutta-percha; ubi-, plasto-, mena-quinones Cofactor in glycosyl transfer to proteins Chemico- and bio-synthesis; function in membranes; control of biochemistry; aberrations in disease Several hundred workers on isoprenoid and glycoprotein biochemistry
W, T, C, and S represent w-terminal, trans-, cis-, and saturated isoprene residues.
he called hepene, an unsaturated hydrocarbon from pig liver, which was most likely dolichol. The presence of solanesol in green leaves alongside plastoquinone-9 had raised the possibility that the former might be related to a precursor of the all-trans C45side chain of the latter. In this respect it was surprising that mammalian tissues containing ubiquinone-10 had yielded mainly dolichol-19 and not all-trans-polyprenol-10. On the other hand, it soon became clear that, although dolichols are found in and probably function throughout the plant kingdom, they rarely accumulate in green leaves. Instead one finds, especially in older leaves, families of tritrans,polycis-prenols (e.g., ficaprenols and castaprenols) (reviewed by Hemming 1974), with no 2,3-saturation and one trans residue more than in the animal dolichols (Fig. 3). In nongreen, woody tissue of plants, the polyisoprenoid alcohols are primarily ditrans,polycis-prenols (e.g., betulaprenols-6 to -10). The biochemical role of these compounds in plant tissues is still not understood. At about the time that eukaryotic polyisoprenoid alcohols were being described, Thorne and Kodicek (1962) were investigating the dependence of lactobacilli on mevalonate as a growth factor. The major metabolite of mevalonate proved to be ditrans,polycis-prenol- 11 (bactoprenol, similar to group 2 of Table 2) (Gough et al. 1970). Also at this time,
FIG.3. The simple role of a polyprenyl phosphate acting as a membrane-bound acceptor and donor, in the transfer of a monosaccharide from a nucleotide donor to a glycan acceptor on opposite sides of a membrane. a and b are specific glycosyltransferases. NDP, nucleoside diphosphate.
-
GDP-Man
+ P-Do1
1 Man-P-Do1
+ GDP
UDP-Glc
+ P-Do1
Glc-P-Do1
+ UDP
+ P-Do1
GlcNAc-PP-Do1 + UMP FIG. 4. The reactions catalysed by eukaryotic endoplasmic reticulum, involving transfer of monosaccharides to dolichyl phosphate (P-Dol).
UDP-GlcNAc
groups of Osborn, Strominger, and Robbins (respectively, Weiner et al. 1965; Andersen et al. 1965; Wright et al. 1965) were developing the concept of lipid intermediates in the biosynthesis of bacterial wall glycans. Strominger and Robbins were able to report that their lipid intermediates were indeed glycan derivatives of bactoprenol phosphate. Lennarz (see Scher et al. 1968) also became deeply involved in bacterial mannosyl transfer via bactoprenol phosphate shortly after this. In this way the role of polyisoprenoid alcohol phosphates in glycosyl transfer was born and shown in its simplest form in Fig. 3. The role of dolichyl phosphate in protein N-glycosylation in animal systems was investigated. Dankert and Leloir initially concentrated on glucosyl transfer to dolichyl phosphate, while my group looked at mannosyl transfer (Fig. 4). Later Behrens and Leloir (1970) led several now well-known international groups in the direction of the surprisingly complex dolichyl phosphate pathway in animal cells (see review, Hemming 1983) (Fig. 5, Table 3). Early evidence for a similar pathway in higher plants came from the laboratories of Elbein (1979). During that time several inhibitors were used to confirm the pathway and its significance to glycoprotein function (Schwarz and Datema 1982; Elbein 1987). The principal inhibitor among these was tunicamycin (Takatsuki et al. 1972), which blocks transfer of N-acetylaminosugar 1-phosphate from nucleotide donors to polyisoprenoid alcohol phosphates (the first step of the dolichol phosphate pathway). This had helped to establish the widespread distribution of the pathway as the major, possibly unique, mechanism of protein N-glycosylation. Tunicamycin does not inhibit protein 0-glycosylation and, therefore, leaves unaffected the dolichyl phosphate mediated, 0-mannosylation of yeast and fungi, as demonstrated elegantly by Tanner and colleagues (Sharma et al. 1974). It should be recognized that this same group made some of the first observations on lipid intermediates in eukaryotic glycosyl transfer to proteins in reports on the yeast system (Tanner 1969).
TABLE2. Summary of naturally occurring polyisoprenoid alcohols Structure Group 1
Size range
all-trans
WT,- ,-OH Group 2
n
Biochem. Cell Biol. Downloaded from www.nrcresearchpress.com by University of Western Ontario on 11/12/14 For personal use only.
=
Some leaves
9,10
ditrans,polycis
WT2C, - ,-OH WT2C, -$-OH Group 3
Location
n = 6-9 n = 15-24
Some woody plant tissue All eucaryotic cells (dolichols)
n n
Leaves Some fungi
tritrans,polycis
WT,C,-,-OH S2T,C, - $-OH
= =
10-13(---22) 19-24
NOTE:Group 1 alcohols have all-trans-isoprenoid chains. Group 2 alcohols are derived from o-trans,transtriisoprenoid and group 3 are derived from w-trans.trans,trans-tetraisoprenoidprecursors. There are now a few examples of where n is larger than the normal range quoted above. W, T, C, and S are defined in Table 1.
J
PROTEIN
FIG. 5. The dolichyl phosphate pathway leading to N-glycosylation of protein. The numbers indicate specific enzymes or groups of enzymes (e.g., steps 3, 4, and 5; each summarizes several enzyme-catalysed reactions).
The synthesis of polyprenols both in vitro and in vivo has received a lot of attention over the years (Fig. 6). The former has involved modification of other natural polyprenols, relying heavily on extensive studies of their distribution in nature (Mankowski et al. 1976; Ibata et al. 1983) or, more recently, on their de novo synthesis (Sato et al. 1983; Jaenicke and Siegmund 1989). It is now possible to synthesize in good yield a particular polyprenol or dolichol of a stipulated stereochemistry and chain length. This may yet enable resolution of the controversial view that particular enzymes, or enzymes in particular cells or conditions, prefer to use a polyprenol of specific chain length or stereochemistry. The biosynthetic pathway of dolichols has been well understood for several years apart from the final stages (Fig. 7). The use of (4R,3R)- and (4S,3~)-[3~]mevalonate as a precursor confirmed that over a wide range of different
TABLE3. Summary of consequences of the dolichol phosphate pathway of N-glycosylation 1.
Allows assembly of pool of oligosaccharidefor immediate transfer to nascent protein
2. Allows control of N-glycosylation independent
of 0-glywsylation 3. Results in transfer of sugars across endoplasmic
reticulum membrane organisms the stereochemical aspects of the structures are decided at each isoprenylation step, there being little, if any, isomerism after synthesis (Hemming 1974). This approach also showed that the saturated a-isoprene residue was biogenetically cis. The origin of the saturated a-residue and
BIOCHEM. CELL BIOL. farnesol4-ts WEE
WEEZZ4-ts
+
Ac
8-CI-(6Z)-nerylbz
MVA \
TL
I I
3
Repeated n
-
1 times
W F E ( 7 n n LIq3
+
VOL. 70, 1992
8-C1-(6~-ci1ronellylbz
DMAPP
Biochem. Cell Biol. Downloaded from www.nrcresearchpress.com by University of Western Ontario on 11/12/14 For personal use only.
ZS WEE(ZZ)nZS-OH (gives dolichols 5 , 7 , 9 , and 11)
WEEZ-OH Then as before (gives dolichols 6, 8, and 10)
FIG. 6. Chemical synthesis of odd- and even-numbered dolichols. ts, tolyl sulfone; bz, benzyl. In this Fig. E- and 2-isoprene residues are equivalent to T (trans) and C (cis), respectively, in Table 1 (after Jaenicke and Siegmund 1989).
FIG. 7. The biosynthesis of dolichol showing critical steps in the process. The question marks indicate uncertainty from there on in the pathway. The involvement of isopentenol is hypothetical. AC, acetate; MVA, mevalonate; IPP, isopentenol pyrophosphate; D M A P P , dimethylaliyl pyrophosphate; F P P , farnesyl pyrophosphate. W, C , T , and S are defined in Table 1.
Biosynthesis
Fatty acyl Do1
catabolism FIG. 8. Summary of reactions that control phosphodolichol concentration in cells. Particular attention is paid to the relevance of dolichol kinase (a), dolichol monophosphate phosphatase (c), and dolichol diphosphate phosphatase ( b ) .
the relationship between dolichol and its phosphorylated form have been the subject of more recent studies in Dallner's laboratory (Ekstrom et al. (1984). Some years ago Allen et al. (1978) and Burton et al. (1979) drew our attention to the importance of polyprenol kinase (and the related phosphatases) and their potential role in controlling the concentrations of dolichol and its phosphate(s) (Fig. 8). Perhaps we will learn more about this later. As mentioned earlier, dolichol was first characterized as a product from a human tissue (kidney). There has been much interest since then on the high concentrations of
dolichols in various human tissues, both healthy and diseased (Rupar and Carroll 1978; Tollbom and Dallner 1986; Wolfe et al. 1982; Pullarkat 1987). Unravelling the relationships between the control of dolichol and glycan biochemistry, which has occupied many of us for several years (Kean 1987; Keller 1987), may be of relevance for a number of disease conditions. Also important in this area will be to understand the physicochemical aspects of the presence of dolichol and its phosphates and glycan derivatives in biological membranes, and the consequences of interactions between the membrane components and this
Biochem. Cell Biol. Downloaded from www.nrcresearchpress.com by University of Western Ontario on 11/12/14 For personal use only.
very long hydrophobic molecule (see Van Duijn et al. 1987; Jensen and Schutzbach 1984; de Ropp et al. 1987). Allen, C.M., Kalin, J.R., and Sack, J. 1978. CTP-dependent dolichol phosphorylation by mammalian cell homogenates. Biochemistry, 17: 5020-5026. Andersen, J.S., Matsuhuashi, M., Haskin, M.A., and Strominger, J.L. 1965. Lipid-phosphoacetylmuramyl-pentapeptideand lipidphosphodisaccharide-pentapeptide: presumed membrane transport intermediates in cell wall synthesis. Proc. Natl. Acad. Sci. U.S.A. 53: 881-889. Behrens, N.H., and Leloir, L.F. 1970. Dolichol monophosphate glucose: an intermediate in glucose transfer in liver. Proc. Natl. Acad. Sci. U.S.A. 66: 153-159. Burgos, J., Hemming, F.W., Pennock, J.F., and Morton, R.A. 1963. Dolichol: a naturally occurring Cleo isoprenoid alcohol. Biochem. J. 88: 470-482. Burton, W.A., Scher, M.G., and Waechter, C.J. 1979. Enzymatic phosphorylation of dolichol in central nervous system. J. Biol. Chem. 254: 7129-7136. Channon, H.J., and Marrian, G.F. 1926. The biological significance of the unsaponifiable matter of oils. 11. An unidentified unsaturated hydrocarbon present in mammalian liver. Biochem. J. 20: 409-418. de Ropp, J.S., Knudsen, M.J., and Troy, F.A. 1987. 'H-NMR investigation of the dynamics and conformation of polyisoprenols in model membranes. Chem. Scr. 27: 101-108. Ekstrom, T.J., Chojnacki, T., and Dallner, L. 1984. Metabolic labelling of dolichol and dolichol phosphate in isolated hepatocytes. J. Biol. Chem. 259: 10 460 - 10 468. Elbein, A.D. 1979. The role of lipid-linked saccharides in the biosynthesis of complex carbohydrates. Annu. Rev. Plant Physiol. 30: 239-272. Elbein, A.D. 1987. Inhibitors of the biosynthesis and processing of N-linked oligosaccharide chains. Annu. Rev. Biochem. 56: 97-534.
Gough, D.P., Kirby, A.L., Richards, J.B., and Hemming, F. W. 1970. The characterization of undecaprenol of Lactobacillus plantarum. Biochem. J. 118: 167-170. Hemming, F.W. 1974. Lipids in glycan biosynthesis. In Biochemistry of lipids. Ser. 1. Vol. 4. Edited by T.W. Goodwin. Butterworths, London. pp. 39-97. Hemming, F.W. 1983. Biosynthesis of dolichols and related compounds. In Biosynthesis of isoprenoid compounds. Vol. 2. Edited by J.W. Porter and S.L. Spurgeon. Wiley, New York. pp. 305-354. Hemming, F.W., Morton, R.A., and Pennock, J.F. 1960. An unsaturated alcohol from human kidney. Biochem. J. 74: 38-39. Ibata, K., Miguno, M., Takigawa, T., and Tanaka, Y. 1983. Longchain betulaprenol-type polyprenols from the leaves of Ginkgo biloba. Biochem. J. 213: 305-31 1. Jaenicke, L., and Siegmund, H.-U. 1989. Synthesis and characterization of dolichols and polyprenols of designed geometry and chain length. Chem. Phys. Lipids, 51: 159-170. Jensen, J.W., and Schutzbach, J.S. 1984. Activation of mannosyltransferase I1 by nonbilayer phospholipids. Biochemistry, 23: 11 15-1119.
Kean, E.L. 1987. Metabolic regulation of the initial reactions of
the dolichol pathway. Chem. Scr. 27: 127-134. Keller, R.K. 1987. The mechanism and regulation of dolichyl phosphate biosynthesis in rat liver. Chem. Scr. 27: 63-70. Mankowski, J., Jankowski, W., Chojnachi, T., and Franke, P. 1976. C55-dolichol:occurrence in pig liver and preparation by hydrogenation of plant undecaprenol. Biochemistry, 15: 2125-2130.
Morton, R.A., Gloor, U., Schindler, O., et al. 1958. Die struktur des ubichinons aus schweineherzen. Helv. Chim. Acta, 41: 2343-2357.
Pennock, J.F., Hemming, F.W., and Morton, R.A. 1960. Dolichol: a naturally occurring isoprenoid alcohol. Nature (London), 186: 470-472. Pullarkat, R.K. 1987. Dolichols and phosphodolichols in ageing and in neurological disorders. Chem. Scr. 27: 85-88. Rowland, R.L., Latimer, R.H., and Giles, J.A. 1956. Flue-cured tobacco. I. Isolation of solanesol, an unsaturated alcohol. J. Am. Chem. Soc. 78: 4680-4685. Rupar, C.A., and Carroll, K.K. 1978. Occurrence of dolichol in human tissues. Lipids, 13: 291-296. Sato, K., Miyamoto, O., Inoue, S., et al. 1983. Stereoselective synthesis of a cisois c,,isoprenoid building block and some all-cispolyprenols. Chem. Lett.: 725-728. Scher, M., Lennarz, W.J., and Sweeley, C.C. 1968. The biosynthesis of mannosyl-1-phosphoryl-polyisoprenolin Micrococcus lysodeikticus and its role in mannan synthesis. Proc. Natl. Acad. Sci. U.S.A. 59: 1313-1320. Schwarz, R.T., and Datema, R. 1982. The lipid pathway of protein glycosylation and its inhibitors: the biological significance of protein-bound carbohydrates. Adv. Carbohydr. Chem. Biochem. 40: 287-379. Sharma, C.B., Babczinski, P., Lehle, L., and Tanner, W. 1974. The role of dolichol monophosphate in glycoprotein biosynthesis in Saccharomyces cerevisiae. Eur. J. Biochem. 46: 35-41. Takatsuki, A., Arima, K., and Tamura, G. 1971. Tunicamycin, a new antibiotic. 1 Isolation and characterization of tunicamycin. J. Antibiot. 24: 215-223. Tanner, W. 1969. A lipid intermediate in mannan biosynthesis in yeast. Biochem. Biophys. Res. Commun. 35: 144-150. Thorne, K.J.T., and Kodicek, E. 1962. The metabolism of acetate and mevalonic acid by lactobacilli. 111. Studies on the unsaponifiable lipids derived from mevalonic acid. Biochim. Biophys. Acta, 59: 295-306. Tollbom, O., and Dallner, G. 1986. Dolichol and dolichyl phosphate in human tissues. Br. J. Exp. Pathol. 67: 759-764. Van Duijn, G., Verhleij, A.J., de Kruiff, B., et al. 1987. Influence of dolichols on lipid polymorphism in model membranes and the consequences for phospholipid flip-flop and vesicle fusion. Chem. Scr. 27: 95-100. Weiner, I.M., Hiyashi, T., Rothfield, L., et al. 1965. Biosynthesis of bacterial lipopolysaccharide V, lipid-linked intermediates in the biosynthesis of the 0-antigen groups of Salmonella typhimurium. Proc. Natl. Acad. Sci. U.S.A. 54: 228-235. Wolfe, L.S., Ng Ying Kim, N.M.K., Palo, J., and Haltia, M. 1982. Raised levels of cerebral cortex colichols in Alzheimer's disease. Lancet ii: 99. Wright, A., Dankert, M., and Robbins, P.W. 1965. Evidence from an intermediate stage in the biosynthesis of the Salmonella Oantigen. Proc. Natl. Acad. Sci. U.S.A. 54: 235-241.
REVIEWS / SYNTH~SES
Dolichol: a curriculum cognitionis FRANK W. HEMMING Biochem. Cell Biol. Downloaded from www.nrcresearchpress.com by University of Western Ontario on 11/12/14 For personal use only.
Department of Biochemistry, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, U.K. Received June 27, 1991 HEMMING, F. W. 1992. Dolichol: a curriculum cognitionis. Biochem. Cell Biol. 70: 377-381. Dolichols were first described about 30 years ago when animal tissues were being examined for the presence of a putative precursor to the polyisoprenoid side chain of ubiquinone. These long-chain 2,3-dihydro-polycis-isoprenoid alcohols are found in all eukaryotic organisms. In many plant tissues they are accompanied by families of other polyisoprenoid alcohols that are usually similar molecules and possess an unsaturated a-isoprene residue. Analogy with the role of bactoprenyl phosphates in the synthesis of bacterial wall glycans led to the discovery that the mono- and di-phosphates of dolichols function as cofactors in protein N-glycosylation, involving the formation of glycosylated derivatives of dolichol as intermediates. Variation of the concentration of dolichyl phosphate was shown to be one way of controlling protein N-glycosylation. This can be achieved by modification of the relative activities of dolichol kinase and dolichol phosphate phosphatase. Modulation of the biosynthetic pathway, still not fully understood, of dolichyl phosphate may also be an important factor. Several disease conditions involve aberrations in these pathways. Key words: dolichols, polyisoprenoid alcohols, N-glycosylation, 0-mannosylation. HEMMING, F. W. 1992. Dolichol: a curriculum cognitionis. Biochem. Cell Biol. 70 : 377-381. La premiere description des dolichols remonte A environ 30 ans lors de l'examen de tissus animaux pour la prtsence d'un precurseur possible de la chaine lattrale polyisoprtno'ide de l'ubiquinone. Ces 2,3-dihydro-polycis-isoprtnoide alcools ti longue chaine sont prtsents dans tous les organismes eucaryotes. Dans beaucoup de tissus vegttaux, ils sont accompagnts de familles d'autres alcools polyisoprtnoides qui sont habituellement des moltcules similaires et possedent un rtsidu a-isoprene non sature. L'analogie avec le r61e des bactoprenyl phosphates dans la synthbe des glycanes des parois bacteriennes a permis la dkcouverte que les mono- et les di-phosphates des dolichols agissent comme cofacteurs dans la N-glycosylation des prottines, impliquant la formation de derives glycosyles du dolichol comme intermediaires. Nous montrons que la variation de la concentration du dolichyl phosphate est une voie de contr6le de la N-glycosylation des proteines. Cela peut s'effectuer par modification des activites relatives de la dolichol kinase et de la dolichol phosphate phosphatase. La modulation de la voie biosynthktique, encore ma1 comprise, du dolichyl phosphate peut Ctre egalement un facteur important. Plusieurs conditions pathologiques impliquent des aberrations dans ces voies. Mots clis : dolichols, alcools, polyisoprtnoides, N-glycosylation, 0-mannosylation. [Traduit par la rtdaction]
Although it is likely that dolichols and related compounds have been components of living systems since early in evolution, they have been recognized for only 30 or so years. Dolichol (Fig. 1) was first described in 1960 in a proceedings abstract (Hemming et al. 1960) and in a short paper (Pennock et al. 1960) (Table 1). It was observed as a major component of the unsaponifiable lipid of human kidney during studies on ubiquinone and related components, which had been shown a little time before to have a polyisoprenoid side chain (Fig. 2) (Morton et al. 1958). The polyisoprenoid nature of the alcohol was based primarily on comparisons of infrared spectrum, iodine number, and results of ozonolysis with solanesol, the all-transpolyprenol-9 (Table 2, Rowland et al. 1956) isolated earlier from tobacco leaves. Saturation of the 2,3-double bond was deduced by infrared spectroscopy, ozonolysis, and the ultraviolet absorption spectrum of dolichaldehyde 2,4-dinitrophenylhydrazone.Chain length was estimated by the extent of dilution of the extinction value (E::!,,) of the ultraviolet and visible absorption spectra of chromophoric acids when esterified to dolichol. As in most areas, advances in this field were technology led. The rapidly developing techniques of NMR, mass spectrometry, and thin-layer chromatography (then new!) quickly ABBREVIATION: NMR, nuclear magnetic resonance. Printed in Canada / Imprime au Canada
L
1n-I FIG. 1. Dolichol, n = 11-23.
FIG. 2. Ubiquinone, n = 6-10.
confirmed and extended these early findings. In particular, NMR showed the presence of two internal isoprene residues in the trans configuration, the rest being cis (see Table 2). It is worth noting that in fact the techniques available 30 or 40 years earlier did not allow Channon and Marrian (1926) to recognize the presence of a hydroxyl group in what
BIOCHEM. CELL BIOL. VOL. 70, 1992
378
TABLE1. Curriculum cognitionis Name (alias)
Dolichol (2,3-dihydropolyisoprenoidalcohol,
Biochem. Cell Biol. Downloaded from www.nrcresearchpress.com by University of Western Ontario on 11/12/14 For personal use only.
hepene?) Date of discovery
Pennock et al. 1960; Burgos et al. 1963; Channon and Marrian 1926
Place of discovery
Liverpool, U.K.
Address Place of formation Place of work Also frequents
No fixed abode Rough endoplasmic reticulum Rough endoplasmic reticulum Other membranes (Golgi, plasma membrane) and lysosomes
Characteristic features
Next of kin (close relations)
Work experience Recent areas of special interest
Referees
Hydrophobic alcohol, many isoprene units in the order WT,C,S-OH (n = 9-20) (plus n + 1, n + 2, n + 3 and n + 4); often as monoor di-phosphatea Families of polyprenols (2-ene); rubber, gutta-percha; ubi-, plasto-, mena-quinones Cofactor in glycosyl transfer to proteins Chemico- and bio-synthesis; function in membranes; control of biochemistry; aberrations in disease Several hundred workers on isoprenoid and glycoprotein biochemistry
W, T, C, and S represent w-terminal, trans-, cis-, and saturated isoprene residues.
he called hepene, an unsaturated hydrocarbon from pig liver, which was most likely dolichol. The presence of solanesol in green leaves alongside plastoquinone-9 had raised the possibility that the former might be related to a precursor of the all-trans C45side chain of the latter. In this respect it was surprising that mammalian tissues containing ubiquinone-10 had yielded mainly dolichol-19 and not all-trans-polyprenol-10. On the other hand, it soon became clear that, although dolichols are found in and probably function throughout the plant kingdom, they rarely accumulate in green leaves. Instead one finds, especially in older leaves, families of tritrans,polycis-prenols (e.g., ficaprenols and castaprenols) (reviewed by Hemming 1974), with no 2,3-saturation and one trans residue more than in the animal dolichols (Fig. 3). In nongreen, woody tissue of plants, the polyisoprenoid alcohols are primarily ditrans,polycis-prenols (e.g., betulaprenols-6 to -10). The biochemical role of these compounds in plant tissues is still not understood. At about the time that eukaryotic polyisoprenoid alcohols were being described, Thorne and Kodicek (1962) were investigating the dependence of lactobacilli on mevalonate as a growth factor. The major metabolite of mevalonate proved to be ditrans,polycis-prenol- 11 (bactoprenol, similar to group 2 of Table 2) (Gough et al. 1970). Also at this time,
FIG.3. The simple role of a polyprenyl phosphate acting as a membrane-bound acceptor and donor, in the transfer of a monosaccharide from a nucleotide donor to a glycan acceptor on opposite sides of a membrane. a and b are specific glycosyltransferases. NDP, nucleoside diphosphate.
-
GDP-Man
+ P-Do1
1 Man-P-Do1
+ GDP
UDP-Glc
+ P-Do1
Glc-P-Do1
+ UDP
+ P-Do1
GlcNAc-PP-Do1 + UMP FIG. 4. The reactions catalysed by eukaryotic endoplasmic reticulum, involving transfer of monosaccharides to dolichyl phosphate (P-Dol).
UDP-GlcNAc
groups of Osborn, Strominger, and Robbins (respectively, Weiner et al. 1965; Andersen et al. 1965; Wright et al. 1965) were developing the concept of lipid intermediates in the biosynthesis of bacterial wall glycans. Strominger and Robbins were able to report that their lipid intermediates were indeed glycan derivatives of bactoprenol phosphate. Lennarz (see Scher et al. 1968) also became deeply involved in bacterial mannosyl transfer via bactoprenol phosphate shortly after this. In this way the role of polyisoprenoid alcohol phosphates in glycosyl transfer was born and shown in its simplest form in Fig. 3. The role of dolichyl phosphate in protein N-glycosylation in animal systems was investigated. Dankert and Leloir initially concentrated on glucosyl transfer to dolichyl phosphate, while my group looked at mannosyl transfer (Fig. 4). Later Behrens and Leloir (1970) led several now well-known international groups in the direction of the surprisingly complex dolichyl phosphate pathway in animal cells (see review, Hemming 1983) (Fig. 5, Table 3). Early evidence for a similar pathway in higher plants came from the laboratories of Elbein (1979). During that time several inhibitors were used to confirm the pathway and its significance to glycoprotein function (Schwarz and Datema 1982; Elbein 1987). The principal inhibitor among these was tunicamycin (Takatsuki et al. 1972), which blocks transfer of N-acetylaminosugar 1-phosphate from nucleotide donors to polyisoprenoid alcohol phosphates (the first step of the dolichol phosphate pathway). This had helped to establish the widespread distribution of the pathway as the major, possibly unique, mechanism of protein N-glycosylation. Tunicamycin does not inhibit protein 0-glycosylation and, therefore, leaves unaffected the dolichyl phosphate mediated, 0-mannosylation of yeast and fungi, as demonstrated elegantly by Tanner and colleagues (Sharma et al. 1974). It should be recognized that this same group made some of the first observations on lipid intermediates in eukaryotic glycosyl transfer to proteins in reports on the yeast system (Tanner 1969).
TABLE2. Summary of naturally occurring polyisoprenoid alcohols Structure Group 1
Size range
all-trans
WT,- ,-OH Group 2
n
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=
Some leaves
9,10
ditrans,polycis
WT2C, - ,-OH WT2C, -$-OH Group 3
Location
n = 6-9 n = 15-24
Some woody plant tissue All eucaryotic cells (dolichols)
n n
Leaves Some fungi
tritrans,polycis
WT,C,-,-OH S2T,C, - $-OH
= =
10-13(---22) 19-24
NOTE:Group 1 alcohols have all-trans-isoprenoid chains. Group 2 alcohols are derived from o-trans,transtriisoprenoid and group 3 are derived from w-trans.trans,trans-tetraisoprenoidprecursors. There are now a few examples of where n is larger than the normal range quoted above. W, T, C, and S are defined in Table 1.
J
PROTEIN
FIG. 5. The dolichyl phosphate pathway leading to N-glycosylation of protein. The numbers indicate specific enzymes or groups of enzymes (e.g., steps 3, 4, and 5; each summarizes several enzyme-catalysed reactions).
The synthesis of polyprenols both in vitro and in vivo has received a lot of attention over the years (Fig. 6). The former has involved modification of other natural polyprenols, relying heavily on extensive studies of their distribution in nature (Mankowski et al. 1976; Ibata et al. 1983) or, more recently, on their de novo synthesis (Sato et al. 1983; Jaenicke and Siegmund 1989). It is now possible to synthesize in good yield a particular polyprenol or dolichol of a stipulated stereochemistry and chain length. This may yet enable resolution of the controversial view that particular enzymes, or enzymes in particular cells or conditions, prefer to use a polyprenol of specific chain length or stereochemistry. The biosynthetic pathway of dolichols has been well understood for several years apart from the final stages (Fig. 7). The use of (4R,3R)- and (4S,3~)-[3~]mevalonate as a precursor confirmed that over a wide range of different
TABLE3. Summary of consequences of the dolichol phosphate pathway of N-glycosylation 1.
Allows assembly of pool of oligosaccharidefor immediate transfer to nascent protein
2. Allows control of N-glycosylation independent
of 0-glywsylation 3. Results in transfer of sugars across endoplasmic
reticulum membrane organisms the stereochemical aspects of the structures are decided at each isoprenylation step, there being little, if any, isomerism after synthesis (Hemming 1974). This approach also showed that the saturated a-isoprene residue was biogenetically cis. The origin of the saturated a-residue and
BIOCHEM. CELL BIOL. farnesol4-ts WEE
WEEZZ4-ts
+
Ac
8-CI-(6Z)-nerylbz
MVA \
TL
I I
3
Repeated n
-
1 times
W F E ( 7 n n LIq3
+
VOL. 70, 1992
8-C1-(6~-ci1ronellylbz
DMAPP
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ZS WEE(ZZ)nZS-OH (gives dolichols 5 , 7 , 9 , and 11)
WEEZ-OH Then as before (gives dolichols 6, 8, and 10)
FIG. 6. Chemical synthesis of odd- and even-numbered dolichols. ts, tolyl sulfone; bz, benzyl. In this Fig. E- and 2-isoprene residues are equivalent to T (trans) and C (cis), respectively, in Table 1 (after Jaenicke and Siegmund 1989).
FIG. 7. The biosynthesis of dolichol showing critical steps in the process. The question marks indicate uncertainty from there on in the pathway. The involvement of isopentenol is hypothetical. AC, acetate; MVA, mevalonate; IPP, isopentenol pyrophosphate; D M A P P , dimethylaliyl pyrophosphate; F P P , farnesyl pyrophosphate. W, C , T , and S are defined in Table 1.
Biosynthesis
Fatty acyl Do1
catabolism FIG. 8. Summary of reactions that control phosphodolichol concentration in cells. Particular attention is paid to the relevance of dolichol kinase (a), dolichol monophosphate phosphatase (c), and dolichol diphosphate phosphatase ( b ) .
the relationship between dolichol and its phosphorylated form have been the subject of more recent studies in Dallner's laboratory (Ekstrom et al. (1984). Some years ago Allen et al. (1978) and Burton et al. (1979) drew our attention to the importance of polyprenol kinase (and the related phosphatases) and their potential role in controlling the concentrations of dolichol and its phosphate(s) (Fig. 8). Perhaps we will learn more about this later. As mentioned earlier, dolichol was first characterized as a product from a human tissue (kidney). There has been much interest since then on the high concentrations of
dolichols in various human tissues, both healthy and diseased (Rupar and Carroll 1978; Tollbom and Dallner 1986; Wolfe et al. 1982; Pullarkat 1987). Unravelling the relationships between the control of dolichol and glycan biochemistry, which has occupied many of us for several years (Kean 1987; Keller 1987), may be of relevance for a number of disease conditions. Also important in this area will be to understand the physicochemical aspects of the presence of dolichol and its phosphates and glycan derivatives in biological membranes, and the consequences of interactions between the membrane components and this
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very long hydrophobic molecule (see Van Duijn et al. 1987; Jensen and Schutzbach 1984; de Ropp et al. 1987). Allen, C.M., Kalin, J.R., and Sack, J. 1978. CTP-dependent dolichol phosphorylation by mammalian cell homogenates. Biochemistry, 17: 5020-5026. Andersen, J.S., Matsuhuashi, M., Haskin, M.A., and Strominger, J.L. 1965. Lipid-phosphoacetylmuramyl-pentapeptideand lipidphosphodisaccharide-pentapeptide: presumed membrane transport intermediates in cell wall synthesis. Proc. Natl. Acad. Sci. U.S.A. 53: 881-889. Behrens, N.H., and Leloir, L.F. 1970. Dolichol monophosphate glucose: an intermediate in glucose transfer in liver. Proc. Natl. Acad. Sci. U.S.A. 66: 153-159. Burgos, J., Hemming, F.W., Pennock, J.F., and Morton, R.A. 1963. Dolichol: a naturally occurring Cleo isoprenoid alcohol. Biochem. J. 88: 470-482. Burton, W.A., Scher, M.G., and Waechter, C.J. 1979. Enzymatic phosphorylation of dolichol in central nervous system. J. Biol. Chem. 254: 7129-7136. Channon, H.J., and Marrian, G.F. 1926. The biological significance of the unsaponifiable matter of oils. 11. An unidentified unsaturated hydrocarbon present in mammalian liver. Biochem. J. 20: 409-418. de Ropp, J.S., Knudsen, M.J., and Troy, F.A. 1987. 'H-NMR investigation of the dynamics and conformation of polyisoprenols in model membranes. Chem. Scr. 27: 101-108. Ekstrom, T.J., Chojnacki, T., and Dallner, L. 1984. Metabolic labelling of dolichol and dolichol phosphate in isolated hepatocytes. J. Biol. Chem. 259: 10 460 - 10 468. Elbein, A.D. 1979. The role of lipid-linked saccharides in the biosynthesis of complex carbohydrates. Annu. Rev. Plant Physiol. 30: 239-272. Elbein, A.D. 1987. Inhibitors of the biosynthesis and processing of N-linked oligosaccharide chains. Annu. Rev. Biochem. 56: 97-534.
Gough, D.P., Kirby, A.L., Richards, J.B., and Hemming, F. W. 1970. The characterization of undecaprenol of Lactobacillus plantarum. Biochem. J. 118: 167-170. Hemming, F.W. 1974. Lipids in glycan biosynthesis. In Biochemistry of lipids. Ser. 1. Vol. 4. Edited by T.W. Goodwin. Butterworths, London. pp. 39-97. Hemming, F.W. 1983. Biosynthesis of dolichols and related compounds. In Biosynthesis of isoprenoid compounds. Vol. 2. Edited by J.W. Porter and S.L. Spurgeon. Wiley, New York. pp. 305-354. Hemming, F.W., Morton, R.A., and Pennock, J.F. 1960. An unsaturated alcohol from human kidney. Biochem. J. 74: 38-39. Ibata, K., Miguno, M., Takigawa, T., and Tanaka, Y. 1983. Longchain betulaprenol-type polyprenols from the leaves of Ginkgo biloba. Biochem. J. 213: 305-31 1. Jaenicke, L., and Siegmund, H.-U. 1989. Synthesis and characterization of dolichols and polyprenols of designed geometry and chain length. Chem. Phys. Lipids, 51: 159-170. Jensen, J.W., and Schutzbach, J.S. 1984. Activation of mannosyltransferase I1 by nonbilayer phospholipids. Biochemistry, 23: 11 15-1119.
Kean, E.L. 1987. Metabolic regulation of the initial reactions of
the dolichol pathway. Chem. Scr. 27: 127-134. Keller, R.K. 1987. The mechanism and regulation of dolichyl phosphate biosynthesis in rat liver. Chem. Scr. 27: 63-70. Mankowski, J., Jankowski, W., Chojnachi, T., and Franke, P. 1976. C55-dolichol:occurrence in pig liver and preparation by hydrogenation of plant undecaprenol. Biochemistry, 15: 2125-2130.
Morton, R.A., Gloor, U., Schindler, O., et al. 1958. Die struktur des ubichinons aus schweineherzen. Helv. Chim. Acta, 41: 2343-2357.
Pennock, J.F., Hemming, F.W., and Morton, R.A. 1960. Dolichol: a naturally occurring isoprenoid alcohol. Nature (London), 186: 470-472. Pullarkat, R.K. 1987. Dolichols and phosphodolichols in ageing and in neurological disorders. Chem. Scr. 27: 85-88. Rowland, R.L., Latimer, R.H., and Giles, J.A. 1956. Flue-cured tobacco. I. Isolation of solanesol, an unsaturated alcohol. J. Am. Chem. Soc. 78: 4680-4685. Rupar, C.A., and Carroll, K.K. 1978. Occurrence of dolichol in human tissues. Lipids, 13: 291-296. Sato, K., Miyamoto, O., Inoue, S., et al. 1983. Stereoselective synthesis of a cisois c,,isoprenoid building block and some all-cispolyprenols. Chem. Lett.: 725-728. Scher, M., Lennarz, W.J., and Sweeley, C.C. 1968. The biosynthesis of mannosyl-1-phosphoryl-polyisoprenolin Micrococcus lysodeikticus and its role in mannan synthesis. Proc. Natl. Acad. Sci. U.S.A. 59: 1313-1320. Schwarz, R.T., and Datema, R. 1982. The lipid pathway of protein glycosylation and its inhibitors: the biological significance of protein-bound carbohydrates. Adv. Carbohydr. Chem. Biochem. 40: 287-379. Sharma, C.B., Babczinski, P., Lehle, L., and Tanner, W. 1974. The role of dolichol monophosphate in glycoprotein biosynthesis in Saccharomyces cerevisiae. Eur. J. Biochem. 46: 35-41. Takatsuki, A., Arima, K., and Tamura, G. 1971. Tunicamycin, a new antibiotic. 1 Isolation and characterization of tunicamycin. J. Antibiot. 24: 215-223. Tanner, W. 1969. A lipid intermediate in mannan biosynthesis in yeast. Biochem. Biophys. Res. Commun. 35: 144-150. Thorne, K.J.T., and Kodicek, E. 1962. The metabolism of acetate and mevalonic acid by lactobacilli. 111. Studies on the unsaponifiable lipids derived from mevalonic acid. Biochim. Biophys. Acta, 59: 295-306. Tollbom, O., and Dallner, G. 1986. Dolichol and dolichyl phosphate in human tissues. Br. J. Exp. Pathol. 67: 759-764. Van Duijn, G., Verhleij, A.J., de Kruiff, B., et al. 1987. Influence of dolichols on lipid polymorphism in model membranes and the consequences for phospholipid flip-flop and vesicle fusion. Chem. Scr. 27: 95-100. Weiner, I.M., Hiyashi, T., Rothfield, L., et al. 1965. Biosynthesis of bacterial lipopolysaccharide V, lipid-linked intermediates in the biosynthesis of the 0-antigen groups of Salmonella typhimurium. Proc. Natl. Acad. Sci. U.S.A. 54: 228-235. Wolfe, L.S., Ng Ying Kim, N.M.K., Palo, J., and Haltia, M. 1982. Raised levels of cerebral cortex colichols in Alzheimer's disease. Lancet ii: 99. Wright, A., Dankert, M., and Robbins, P.W. 1965. Evidence from an intermediate stage in the biosynthesis of the Salmonella Oantigen. Proc. Natl. Acad. Sci. U.S.A. 54: 235-241.
