262
Biochimica et Biophvsica Acta, 1(t87 (1990) 262 263 Elsevier
B B A Report - Short S e q u e n c e - P a p e r
BBAEXP 90197
A c D N A clone homologous to Drosophila F elements from an imaginal discs poly(A) + library Angela Tino 1, Franco Graziani 1 and Pier Paolo Di Nocera ~,2 Internatmnal Institute of Genetics and Biophysics, CNR, Naples and " Dipartimento di Biologia, Facolta' di Science. Universita' di Lecce, Lecce (Italy)
(Received 18 July 1990)
Key words: Mobile DNA element: Retrotransposition; D N A element
A cDNA clone (F-idl) homologous to Drosophila F elements has been isolated from a cDNA library prepared from poly(A) ÷ RNA derived from imaginal discs. The F-idl insert is identical to the 3' end terminus of Fw, an element inserted at the white locus upon irradiation. The isolation of F-idl provides the first evidence that F elements are expressed in the fruit fly life.
[]
ORF1
I~
ORF2
~ (A) n sufrlx Fid-
I
1CTTGCTCTACAATTC] A r A r TGAAAC~JAAF C- BGACC 1AT GGC- CACAG~ ] ATGGGGCAATGCCAO~/AA~,A~,~ AA r ~ " AC A TCK[TCAGC GAGCACAATCAAAGA f ] C TGAGAACCA] CACT GGGGCACCGTGGT ACOTTCGGAGT GAAAACA r LLAA;~ GAGACTTMATATCCCA] CAG] TACCAACGCAA ICACCGAAC" ] AAGGAAAAA- ACC i A FAGCAAG~. l ~LACALGCAE : ~ . AAC~ACCTAGCGCGAGGTC 7AATCCAGCTCAGCAGCCG [ f CCCG [ C ] CCGGCGAAAGGACC ~ACCAACC AOCGAA A A A ] TRTTAGGGCCGT iIMiAAACATAGAACAGTTGGA/~k~,~I,~ATACAACr O] rCAAAAAAi ACTTS] ~A~ A(; I AAGA- "
A=
ACTTA]~FGTTAG]~C ] l A i AC AAbAAO.~ / - C ,~A - AAA i AAAAAGC AAAG r A A A A A A A A A A A A A A A A ~ / ~ A A ~
Fig. 1. Schematic representation of a complete F element. Lines below denote the region homologous to suffix elements (6) and to the F-idl clone. The nucleotide sequence of the F-idl insert is reported below. Underlined residues correspond to the end of the region encoding F-orf2.
D. melanogaster F elements are D N A mobile sequences that exhibit size heterogeneity at the 5' end and invariably terminate at the 3' end in oligo (A) tails preceded by polyadenylylation signals [1,2]. Full length F elements potentially encode two proteins (Fig. 1), one (F-orfl) structurally related to nucleic acid binding proteins originated by cleavage of retroviral gag polyproteins, the other (F-orf2) exhibiting homology to known reverse transcriptases [3,4]. The structural organization
The sequence data in this paper have been submitted to the E M B L / Genbank Data Libraries under the accession number X52682.
Correspondence: P.P. Di Nocera, International Institute of Genetics and Biophysics, CNR, Via Marconi 10, Naples, Italy.
and the coding capacity suggest that F elements originate from the self-mediated c D N A conversion of full size transcripts initiated from an internal polymerase II promoter [3,4]. Utilizing as a probe a 2.9 kb long HindlII-BgllI fragment from Fw [4] we have screened a c D N A library derived from imaginal discs poly(A) + R N A kindly provided by Dr. T. Kornberg. Out of 10 6 recombinants plated, a clone (F-idl) corresponding to the 3' end of an F element was found. The nucleotide sequence of the F-idl insert, determined on both strands by the dideoxy chain termination method as modified by Hattori and Sakaki [5], is reported in Fig. 1. Transcripts homologous to F sequences have not been detected in the whole animal [1], and this report provides direct evidence that F elements are transcribed in vivo. The size of the F-idl insert rules out that it
0167-4781/90/$03.50 © 1990 Elsevier Science Publishers B.V. (Biomedical Division)
263 might correspond to a suffix element, a kind of extremely 3' truncated member of the F family of fixed length (see Fig. 1) present in the untranslated portion of a large variety of Drosophila transcripts [6]. We are investigating whether the isolation of F-idl from an imaginal discs cDNA library might be correlated to a pattern of expression restricted to specific cell populations. Imaginal discs are composed by undifferentiated cells, and in this context, it is of interest to notice that full length transcripts homologous to L1, a major family of long repeated DNA dispersed in the human genome that are closely related to F dements [2-4], have been detected so far only in undifferentiated human teratocarcinoma cells [7]. F-idl is identical in sequence to Fw, an F element inserted into the white locus after irradiation [4]. This finding supports the notion that only a few F family members might be transcriptionally active and able to retrotranspose.
This research was in part supported by Progetto Finalizzato Biotecnologie e Biostrumentazione and Progetto Finalizzato Ingegneria Genetica.
References 1 Dawid, I.B., Long, E.O., Di Nocera, P.P. and Pardue, M.L. (1981) Cell 25, 399-408. 2 Di Nocera, P.P., Digan, M.E. and Dawid, I.B. (1983) J. Mol. Biol. 168, 715-728. 3 Di Nocera, P.P. (1988) Nucleic Acids Res. 16, 4041-4052. 4 Di Nocera, P.P. and Casari, G. (1987) Proc. Natl. Acad. Sci. USA 84, 5843-5847. 5 Hattori, M. and Sakaki, Y. (1986) Anal. Biochem. 152, 2312-238. 6 Tchurikov, N.A., Ebralidze, A.K. and Georgiev, G.P. (1986) EMBO J. 5, 2341-2347. 7 Skowronski, J. and Singer, M.F. (1986) Cold Spring Harbor Symp. Quant. Biol. 51, 457-464.
Biochimica et Biophvsica Acta, 1(t87 (1990) 262 263 Elsevier
B B A Report - Short S e q u e n c e - P a p e r
BBAEXP 90197
A c D N A clone homologous to Drosophila F elements from an imaginal discs poly(A) + library Angela Tino 1, Franco Graziani 1 and Pier Paolo Di Nocera ~,2 Internatmnal Institute of Genetics and Biophysics, CNR, Naples and " Dipartimento di Biologia, Facolta' di Science. Universita' di Lecce, Lecce (Italy)
(Received 18 July 1990)
Key words: Mobile DNA element: Retrotransposition; D N A element
A cDNA clone (F-idl) homologous to Drosophila F elements has been isolated from a cDNA library prepared from poly(A) ÷ RNA derived from imaginal discs. The F-idl insert is identical to the 3' end terminus of Fw, an element inserted at the white locus upon irradiation. The isolation of F-idl provides the first evidence that F elements are expressed in the fruit fly life.
[]
ORF1
I~
ORF2
~ (A) n sufrlx Fid-
I
1CTTGCTCTACAATTC] A r A r TGAAAC~JAAF C- BGACC 1AT GGC- CACAG~ ] ATGGGGCAATGCCAO~/AA~,A~,~ AA r ~ " AC A TCK[TCAGC GAGCACAATCAAAGA f ] C TGAGAACCA] CACT GGGGCACCGTGGT ACOTTCGGAGT GAAAACA r LLAA;~ GAGACTTMATATCCCA] CAG] TACCAACGCAA ICACCGAAC" ] AAGGAAAAA- ACC i A FAGCAAG~. l ~LACALGCAE : ~ . AAC~ACCTAGCGCGAGGTC 7AATCCAGCTCAGCAGCCG [ f CCCG [ C ] CCGGCGAAAGGACC ~ACCAACC AOCGAA A A A ] TRTTAGGGCCGT iIMiAAACATAGAACAGTTGGA/~k~,~I,~ATACAACr O] rCAAAAAAi ACTTS] ~A~ A(; I AAGA- "
A=
ACTTA]~FGTTAG]~C ] l A i AC AAbAAO.~ / - C ,~A - AAA i AAAAAGC AAAG r A A A A A A A A A A A A A A A A ~ / ~ A A ~
Fig. 1. Schematic representation of a complete F element. Lines below denote the region homologous to suffix elements (6) and to the F-idl clone. The nucleotide sequence of the F-idl insert is reported below. Underlined residues correspond to the end of the region encoding F-orf2.
D. melanogaster F elements are D N A mobile sequences that exhibit size heterogeneity at the 5' end and invariably terminate at the 3' end in oligo (A) tails preceded by polyadenylylation signals [1,2]. Full length F elements potentially encode two proteins (Fig. 1), one (F-orfl) structurally related to nucleic acid binding proteins originated by cleavage of retroviral gag polyproteins, the other (F-orf2) exhibiting homology to known reverse transcriptases [3,4]. The structural organization
The sequence data in this paper have been submitted to the E M B L / Genbank Data Libraries under the accession number X52682.
Correspondence: P.P. Di Nocera, International Institute of Genetics and Biophysics, CNR, Via Marconi 10, Naples, Italy.
and the coding capacity suggest that F elements originate from the self-mediated c D N A conversion of full size transcripts initiated from an internal polymerase II promoter [3,4]. Utilizing as a probe a 2.9 kb long HindlII-BgllI fragment from Fw [4] we have screened a c D N A library derived from imaginal discs poly(A) + R N A kindly provided by Dr. T. Kornberg. Out of 10 6 recombinants plated, a clone (F-idl) corresponding to the 3' end of an F element was found. The nucleotide sequence of the F-idl insert, determined on both strands by the dideoxy chain termination method as modified by Hattori and Sakaki [5], is reported in Fig. 1. Transcripts homologous to F sequences have not been detected in the whole animal [1], and this report provides direct evidence that F elements are transcribed in vivo. The size of the F-idl insert rules out that it
0167-4781/90/$03.50 © 1990 Elsevier Science Publishers B.V. (Biomedical Division)
263 might correspond to a suffix element, a kind of extremely 3' truncated member of the F family of fixed length (see Fig. 1) present in the untranslated portion of a large variety of Drosophila transcripts [6]. We are investigating whether the isolation of F-idl from an imaginal discs cDNA library might be correlated to a pattern of expression restricted to specific cell populations. Imaginal discs are composed by undifferentiated cells, and in this context, it is of interest to notice that full length transcripts homologous to L1, a major family of long repeated DNA dispersed in the human genome that are closely related to F dements [2-4], have been detected so far only in undifferentiated human teratocarcinoma cells [7]. F-idl is identical in sequence to Fw, an F element inserted into the white locus after irradiation [4]. This finding supports the notion that only a few F family members might be transcriptionally active and able to retrotranspose.
This research was in part supported by Progetto Finalizzato Biotecnologie e Biostrumentazione and Progetto Finalizzato Ingegneria Genetica.
References 1 Dawid, I.B., Long, E.O., Di Nocera, P.P. and Pardue, M.L. (1981) Cell 25, 399-408. 2 Di Nocera, P.P., Digan, M.E. and Dawid, I.B. (1983) J. Mol. Biol. 168, 715-728. 3 Di Nocera, P.P. (1988) Nucleic Acids Res. 16, 4041-4052. 4 Di Nocera, P.P. and Casari, G. (1987) Proc. Natl. Acad. Sci. USA 84, 5843-5847. 5 Hattori, M. and Sakaki, Y. (1986) Anal. Biochem. 152, 2312-238. 6 Tchurikov, N.A., Ebralidze, A.K. and Georgiev, G.P. (1986) EMBO J. 5, 2341-2347. 7 Skowronski, J. and Singer, M.F. (1986) Cold Spring Harbor Symp. Quant. Biol. 51, 457-464.
