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. 1997 Jul 16;16(14):4448–4455. doi: 10.1093/emboj/16.14.4448

A LINE-like transposable element in Drosophila, the I factor, encodes a protein with properties similar to those of retroviral nucleocapsids.

A Dawson 1, E Hartswood 1, T Paterson 1, D J Finnegan 1
PMCID: PMC1170071  PMID: 9250689

Abstract

I factors are members of the LINE-like family of transposable elements and move by reverse transcription of an RNA intermediate. Complete I factors contain two open reading frames. The amino acid sequence encoded by the first of these, ORF1, includes the motif CX2CX4HX4C that is characteristic of the nucleocapsid domain of retroviral gag polypeptides followed by a copy of the slightly different sequences CX2CX4HX6C and CX2CX9HX6C. The function of this protein is unknown. We have expressed this protein in Escherichia coli and Spodoptera frugiperda cells and have shown that it binds both DNA and RNA but without any evidence for sequence specificity. The properties of deletion derivatives of the protein indicate that more than one region is responsible for DNA binding and that the CCHC motif is not essential for this. The ORF1 protein expressed in either E. coli or Spodoptera cells forms high molecular weight structures that require the region of the protein including the CCHC motif for their formation. This protein can also accelerate the annealing of complementary single-stranded oligonucleotides. These results suggest that this protein may associate with the RNA transposition intermediates of the I factor to form particles that enter the nucleus during transposition and that it may stimulate both the priming of reverse transcription and integration. This may be generally true for the product of the first open reading frame of LINE-like elements.

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Selected References

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  1. Aksoy S., Williams S., Chang S., Richards F. F. SLACS retrotransposon from Trypanosoma brucei gambiense is similar to mammalian LINEs. Nucleic Acids Res. 1990 Feb 25;18(4):785–792. doi: 10.1093/nar/18.4.785. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Aronoff R., Hajjar A. M., Linial M. L. Avian retroviral RNA encapsidation: reexamination of functional 5' RNA sequences and the role of nucleocapsid Cys-His motifs. J Virol. 1993 Jan;67(1):178–188. doi: 10.1128/jvi.67.1.178-188.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Berg J. M. Zinc fingers and other metal-binding domains. Elements for interactions between macromolecules. J Biol Chem. 1990 Apr 25;265(12):6513–6516. [PubMed] [Google Scholar]
  4. Boeke J. D., Corces V. G. Transcription and reverse transcription of retrotransposons. Annu Rev Microbiol. 1989;43:403–434. doi: 10.1146/annurev.mi.43.100189.002155. [DOI] [PubMed] [Google Scholar]
  5. Bouhidel K., Terzian C., Pinon H. The full-length transcript of the I factor, a LINE element of Drosophila melanogaster, is a potential bicistronic RNA messenger. Nucleic Acids Res. 1994 Jun 25;22(12):2370–2374. doi: 10.1093/nar/22.12.2370. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Bucheton A. I transposable elements and I-R hybrid dysgenesis in Drosophila. Trends Genet. 1990 Jan;6(1):16–21. doi: 10.1016/0168-9525(90)90044-7. [DOI] [PubMed] [Google Scholar]
  7. Bucheton A., Paro R., Sang H. M., Pelisson A., Finnegan D. J. The molecular basis of I-R hybrid dysgenesis in Drosophila melanogaster: identification, cloning, and properties of the I factor. Cell. 1984 Aug;38(1):153–163. doi: 10.1016/0092-8674(84)90536-1. [DOI] [PubMed] [Google Scholar]
  8. Cambareri E. B., Helber J., Kinsey J. A. Tad1-1, an active LINE-like element of Neurospora crassa. Mol Gen Genet. 1994 Mar;242(6):658–665. doi: 10.1007/BF00283420. [DOI] [PubMed] [Google Scholar]
  9. Chaboissier M. C., Busseau I., Prosser J., Finnegan D. J., Bucheton A. Identification of a potential RNA intermediate for transposition of the LINE-like element I factor in Drosophila melanogaster. EMBO J. 1990 Nov;9(11):3557–3563. doi: 10.1002/j.1460-2075.1990.tb07566.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. D'Ambrosio E., Waitzkin S. D., Witney F. R., Salemme A., Furano A. V. Structure of the highly repeated, long interspersed DNA family (LINE or L1Rn) of the rat. Mol Cell Biol. 1986 Feb;6(2):411–424. doi: 10.1128/mcb.6.2.411. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Di Nocera P. P. Close relationship between non-viral retroposons in Drosophila melanogaster. Nucleic Acids Res. 1988 May 11;16(9):4041–4052. doi: 10.1093/nar/16.9.4041. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Dorfman T., Luban J., Goff S. P., Haseltine W. A., Göttlinger H. G. Mapping of functionally important residues of a cysteine-histidine box in the human immunodeficiency virus type 1 nucleocapsid protein. J Virol. 1993 Oct;67(10):6159–6169. doi: 10.1128/jvi.67.10.6159-6169.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Fawcett D. H., Lister C. K., Kellett E., Finnegan D. J. Transposable elements controlling I-R hybrid dysgenesis in D. melanogaster are similar to mammalian LINEs. Cell. 1986 Dec 26;47(6):1007–1015. doi: 10.1016/0092-8674(86)90815-9. [DOI] [PubMed] [Google Scholar]
  14. Feng Q., Moran J. V., Kazazian H. H., Jr, Boeke J. D. Human L1 retrotransposon encodes a conserved endonuclease required for retrotransposition. Cell. 1996 Nov 29;87(5):905–916. doi: 10.1016/s0092-8674(00)81997-2. [DOI] [PubMed] [Google Scholar]
  15. Franck A., Guilley H., Jonard G., Richards K., Hirth L. Nucleotide sequence of cauliflower mosaic virus DNA. Cell. 1980 Aug;21(1):285–294. doi: 10.1016/0092-8674(80)90136-1. [DOI] [PubMed] [Google Scholar]
  16. Franke E. K., Yuan H. E., Bossolt K. L., Goff S. P., Luban J. Specificity and sequence requirements for interactions between various retroviral Gag proteins. J Virol. 1994 Aug;68(8):5300–5305. doi: 10.1128/jvi.68.8.5300-5305.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Gabriel A., Boeke J. D. Reverse transcriptase encoded by a retrotransposon from the trypanosomatid Crithidia fasciculata. Proc Natl Acad Sci U S A. 1991 Nov 1;88(21):9794–9798. doi: 10.1073/pnas.88.21.9794. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. George J. A., Burke W. D., Eickbush T. H. Analysis of the 5' junctions of R2 insertions with the 28S gene: implications for non-LTR retrotransposition. Genetics. 1996 Mar;142(3):853–863. doi: 10.1093/genetics/142.3.853. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Hohjoh H., Singer M. F. Cytoplasmic ribonucleoprotein complexes containing human LINE-1 protein and RNA. EMBO J. 1996 Feb 1;15(3):630–639. [PMC free article] [PubMed] [Google Scholar]
  20. Jensen S., Cavarec L., Gassama M. P., Heidmann T. Defective I elements introduced into Drosophila as transgenes can regulate reactivity and prevent I-R hybrid dysgenesis. Mol Gen Genet. 1995 Aug 30;248(4):381–390. doi: 10.1007/BF02191637. [DOI] [PubMed] [Google Scholar]
  21. Klikova M., Rhee S. S., Hunter E., Ruml T. Efficient in vivo and in vitro assembly of retroviral capsids from Gag precursor proteins expressed in bacteria. J Virol. 1995 Feb;69(2):1093–1098. doi: 10.1128/jvi.69.2.1093-1098.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Leeton P. R., Smyth D. R. An abundant LINE-like element amplified in the genome of Lilium speciosum. Mol Gen Genet. 1993 Feb;237(1-2):97–104. doi: 10.1007/BF00282789. [DOI] [PubMed] [Google Scholar]
  23. Luan D. D., Korman M. H., Jakubczak J. L., Eickbush T. H. Reverse transcription of R2Bm RNA is primed by a nick at the chromosomal target site: a mechanism for non-LTR retrotransposition. Cell. 1993 Feb 26;72(4):595–605. doi: 10.1016/0092-8674(93)90078-5. [DOI] [PubMed] [Google Scholar]
  24. Martin S. L. Ribonucleoprotein particles with LINE-1 RNA in mouse embryonal carcinoma cells. Mol Cell Biol. 1991 Sep;11(9):4804–4807. doi: 10.1128/mcb.11.9.4804. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Mathias S. L., Scott A. F., Kazazian H. H., Jr, Boeke J. D., Gabriel A. Reverse transcriptase encoded by a human transposable element. Science. 1991 Dec 20;254(5039):1808–1810. doi: 10.1126/science.1722352. [DOI] [PubMed] [Google Scholar]
  26. Priimägi A. F., Mizrokhi L. J., Ilyin Y. V. The Drosophila mobile element jockey belongs to LINEs and contains coding sequences homologous to some retroviral proteins. Gene. 1988 Oct 30;70(2):253–262. doi: 10.1016/0378-1119(88)90197-7. [DOI] [PubMed] [Google Scholar]
  27. Pritchard M. A., Dura J. M., Pélisson A., Bucheton A., Finnegan D. J. A cloned I-factor is fully functional in Drosophila melanogaster. Mol Gen Genet. 1988 Nov;214(3):533–540. doi: 10.1007/BF00330491. [DOI] [PubMed] [Google Scholar]
  28. Pélisson A., Song S. U., Prud'homme N., Smith P. A., Bucheton A., Corces V. G. Gypsy transposition correlates with the production of a retroviral envelope-like protein under the tissue-specific control of the Drosophila flamenco gene. EMBO J. 1994 Sep 15;13(18):4401–4411. doi: 10.1002/j.1460-2075.1994.tb06760.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Song S. U., Gerasimova T., Kurkulos M., Boeke J. D., Corces V. G. An env-like protein encoded by a Drosophila retroelement: evidence that gypsy is an infectious retrovirus. Genes Dev. 1994 Sep 1;8(17):2046–2057. doi: 10.1101/gad.8.17.2046. [DOI] [PubMed] [Google Scholar]
  30. Studier F. W., Rosenberg A. H., Dunn J. J., Dubendorff J. W. Use of T7 RNA polymerase to direct expression of cloned genes. Methods Enzymol. 1990;185:60–89. doi: 10.1016/0076-6879(90)85008-c. [DOI] [PubMed] [Google Scholar]
  31. Thomsen D. R., Meyer A. L., Post L. E. Expression of feline leukaemia virus gp85 and gag proteins and assembly into virus-like particles using the baculovirus expression vector system. J Gen Virol. 1992 Jul;73(Pt 7):1819–1824. doi: 10.1099/0022-1317-73-7-1819. [DOI] [PubMed] [Google Scholar]
  32. Udomkit A., Forbes S., McLean C., Arkhipova I., Finnegan D. J. Control of expression of the I factor, a LINE-like transposable element in Drosophila melanogaster. EMBO J. 1996 Jun 17;15(12):3174–3181. [PMC free article] [PubMed] [Google Scholar]
  33. Wright D. A., Ke N., Smalle J., Hauge B. M., Goodman H. M., Voytas D. F. Multiple non-LTR retrotransposons in the genome of Arabidopsis thaliana. Genetics. 1996 Feb;142(2):569–578. doi: 10.1093/genetics/142.2.569. [DOI] [PMC free article] [PubMed] [Google Scholar]

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