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. 2004 Apr 29;38(1):309–316. doi: 10.1016/0092-8674(84)90552-X

Trypanosome mRNAs share a common 5′ spliced leader sequence

Marilyn Parsons 1, Richard G Nelson 1, Kenneth P Watkins 1, Nina Agabian 1
PMCID: PMC7133311  PMID: 6088073

Abstract

A 5′-terminal leader sequence of 35 nucleotides was found to be present on multiple trypanosome RNAs. Based on its representation in cDNA libraries, we estimate that many, if not all, trypanosome mRNAs contain this leader. This same leader was originally identified on mRNAs encoding the molecules responsible for antigenic variation, variant surface glycoproteins. Studies of selected cDNAs containing this leader sequence revealed that leader-containing transcripts can be stage-specific, stage-regulated, or constitutive. They can be abundant or rare, and transcribed from single or multigene families. No linkage between the genomic leader sequences and the structural gene exons was observed. Possible mechanisms by which the leader sequences are added to trypanosome mRNAs are discussed.

References

  1. Agabian N., Thomashow L., Milhausen M., Stuart K. Structural analysis of variant and invariant genes in trypanosomes. Am. J. Trop. Med. Hyg. 1980;29(5):1043–1049. doi: 10.4269/ajtmh.1980.29.1043. Suppl. [DOI] [PubMed] [Google Scholar]
  2. Bernards A., Van der Ploeg L.H.T., Frasch A.C.C., Borst P., Boothroyd J.C., Coleman S., Cross G.A.M. Activation of trypanosome surface glycoprotein genes involves a duplication-transposition leading to an altered 3′ end. Cell. 1981;27:497–505. doi: 10.1016/0092-8674(81)90391-3. [DOI] [PubMed] [Google Scholar]
  3. Bernards A., Michels P., Lincke C., Borst P. Growth of chromosome ends in multiplying trypanosomes. Nature. 1983;303:592–597. doi: 10.1038/303592a0. [DOI] [PubMed] [Google Scholar]
  4. Boothroyd J., Cross G. Transcripts coding for variant surface glycoproteins of Trypanosoma brucei have a short, identical exon at their 5′ end. Gene. 1982;20:281–289. doi: 10.1016/0378-1119(82)90046-4. [DOI] [PubMed] [Google Scholar]
  5. Buck G., Longacre S., Raibaud A., Hibner U., Giroud C., Baltz T., Baltz D., Eisen H. Stability of expression-linked surface antigen gene in Trypanosoma equiperdum. Nature. 1984;307:563–566. doi: 10.1038/307563a0. [DOI] [PubMed] [Google Scholar]
  6. Childs G., Maxson R., Cohn R.H., Kedes L. Orphons: dispersed genetic elements derived from tandem repetitive genes of eucaryotes. Cell. 1981;23:651–663. doi: 10.1016/0092-8674(81)90428-1. [DOI] [PubMed] [Google Scholar]
  7. Delange T., Borst P. Genomic environment of the expression linked extra copies for surface antigens of Trypanosoma brucei resembles the end of a chromosome. Nature. 1982;299:451–453. doi: 10.1038/299451a0. [DOI] [PubMed] [Google Scholar]
  8. Delange T., Liu A.Y.C., Van der Ploeg L.H.T., Borst P., Trompe M.C., van Boom J.H. Tandem repetition of the 5′ mini-exon of variant surface glycoprotein genes: a multiple promoter for VSG gene transcription? Cell. 1983;34:891–900. doi: 10.1016/0092-8674(83)90546-9. [DOI] [PubMed] [Google Scholar]
  9. Hanas J., Linden G., Stuart K. Mitochondrial and cytoplasmic ribosomes and their activity in blood and culture forms of Trypanosoma brucei. J. Cell Biol. 1975;65:103–111. doi: 10.1083/jcb.65.1.103. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Hoeijmakers J.H.J., Frasch A.C.C., Bernards A., Borst P., Cross G.A.M. Novel expression-linked copies of the genes for variant surface antigens in trypanosomes. Nature. 1980;284:78–80. doi: 10.1038/284078a0. [DOI] [PubMed] [Google Scholar]
  11. Hoeijmakers J.H.J., Borst P., Van den Burg J., Weissmann C., Cross G.A.M. The isolation of plasmids containing DNA complementary to messenger RNA for variant surface glycoproteins of Trypanosoma brucei. Gene. 1980;8:391–417. doi: 10.1016/0378-1119(80)90043-8. [DOI] [PubMed] [Google Scholar]
  12. Longacre S., Hibner U., Raibaud A., Eisen H., Baltz T., Giroud C., Baltz T. DNA rearrangements and antigenic variation in Trypanosoma equiperdum: multiple expression-linked sites in independent isolates of trypanosomes expressing the same antigen. Mol. Cell. Biol. 1983;3:399–409. doi: 10.1128/mcb.3.3.399. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Michiels F., Matthyssens G., Kronenburger P., Pays E., Dero B., Van Assel S., Darville M., Cravador A., Steinert M., Hamers R. Gene activation and re-expression of a Trypanosoma brucei variant surface glycoprotein. EMBO J. 1983;2:1185–1192. doi: 10.1002/j.1460-2075.1983.tb01565.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Milhausen M., Nelson R., Parsons M., Newport G., Stuart K., Agabian N. Molecular characterization of initial variants from the IsTat 1 serodeme of Trypanosoma brucei. Mol. Biochem. Parasitol. 1983;9:241–254. doi: 10.1016/0166-6851(83)90100-7. [DOI] [PubMed] [Google Scholar]
  15. Milner R., Bloom F., Lai C., Lerner R., Sutcliffe G. Vol. 81. 1984. Bran-specific genes have identifier sequences in their introns; pp. 713–717. (Proc. Nat. Acad. Sci. USA). [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Murphy D., Brickell P.M., Latchman D.S., Willison K., Rigby P.W.J. Transcripts regulated during normal embryonic development and oncogenic transformation share a repetitive element. Cell. 1983;35:865–871. doi: 10.1016/0092-8674(83)90119-8. [DOI] [PubMed] [Google Scholar]
  17. Nelson R.G., Parsons M., Barr P.J., Stuart K., Selkirk M., Agabian N. Sequences homologous to the variant antigen mRNA spliced leader are located in tandem repeats and variable orphons in Trypanosoma brucei. Cell. 1983;34:901–909. doi: 10.1016/0092-8674(83)90547-0. [DOI] [PubMed] [Google Scholar]
  18. Nelson R., Parsons M., Selkirk M., Barr P., Agabian N. Sequences homologous to variant antigen mRNA spliced leader in Trypanosomatidae which do not undergo antigenic variation. Nature. 1984;308:665–667. doi: 10.1038/308665a0. [DOI] [PubMed] [Google Scholar]
  19. Overath P., Czichos J., Stock U., Nonnengasser C. Repression of glycoprotein synthesis and release of surface coat during transformation of Trypanosoma brucei. EMBO J. 1983;2:1721–1729. doi: 10.1002/j.1460-2075.1983.tb01648.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Parsons M., Nelson R.G., Newport G., Milhausen M., Stuart K., Agabian N. Genomic organization of Trypanosoma brucei variant antigen gene families in sequential parasitemias. Mol. Biochem. Parasitol. 1983;9:255–269. doi: 10.1016/0166-6851(83)90101-9. [DOI] [PubMed] [Google Scholar]
  21. Parsons M., Nelson R., Agabian N. Antigenic variation in african trypanosomes: DNA rearrangements program immune evasion. Immunol. Today. 1984;5:43–50. doi: 10.1016/0167-5699(84)90028-8. [DOI] [PubMed] [Google Scholar]
  22. Parsons M., Nelson R., Stuart K., Agabian N. Vol. 81. 1984. Variant antigen genes of Trypanosoma brucei: genomic alteration of a spliced leader orphon and retention of expression linked copies during differentiation; pp. 684–688. (Proc. Nat. Acad. Sci. USA). [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Pays E., Delronche M., Lheureux M., Vervoort T., Bloch J., Gannon F., Steinert M. Cloning and characterization of DNA sequences complementary to messenger ribonucleic acids coding for the synthesis of two surface antigens of Trypanosoma brucei. Nucl. Acids Res. 1980;8:5965–5981. doi: 10.1093/nar/8.24.5965. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Pays E., Van Meirvenne N., Leray D., Steinert M. Vol. 78. 1981. Gene duplication and transposition linked to antigenic variation in Trypanosoma brucei; pp. 2673–2677. (Proc. Nat. Acad. Sci. USA). [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Pays E., Lheureux M., Steinert M. The expression-linked copy of surface antigen gene in Trypanosoma is probably the one transcribed. Nature. 1981;292:265–267. doi: 10.1038/292265a0. [DOI] [PubMed] [Google Scholar]
  26. Plotch S.J., Bouloy M., Ulmanen I., Krug R.M. A unique cap (m7GpppXm)-dependent influenza virion endonuclease cleaves capped RNAs to generate the primers that initiate viral RNA transcription. Cell. 1981;23:847–858. doi: 10.1016/0092-8674(81)90449-9. [DOI] [PubMed] [Google Scholar]
  27. Sanger F., Nicklen S., Coulsen A. Vol. 74. 1977. DNA sequencing with chain-terminating inhibitors; pp. 5463–5467. (Proc. Nat. Acad. Sci. USA). [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Spaan W., Delius H., Skinner M., Armstrong J., Rottier P., Smeekens S., van der Zeijst B., Siddell S. Coronavirus mRNA synthesis involves fusion of non-contiguous sequences. EMBO J. 1983;2:1839–1844. doi: 10.1002/j.1460-2075.1983.tb01667.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Stuart K., Gobright E., Jenni L., Milhausen M., Thomashow L., Agabian N. The IsTat serodeme of T. brucei: development of a new T. b. brucei serodeme and characterization of early variants. Parasitology. 1984 in press. [PubMed] [Google Scholar]
  30. Sutcliffe J., Milner R., Gottesfeld J., Lerner R. Identifier sequences are transcribed specifically in brain. Nature. 1984;308:237–241. doi: 10.1038/308237a0. [DOI] [PubMed] [Google Scholar]
  31. Tchurikov N., Naumova A., Zelentsova E., Georgiev G. A cloned unique gene of Drosophila melanogaster containing a repetitive 3′ exon whose sequence is present at the 3′ ends of many different mRNAs. Cell. 1982;28:365–373. doi: 10.1016/0092-8674(82)90354-3. [DOI] [PubMed] [Google Scholar]
  32. Van der Ploeg L.H.T., Valerio D., Delange T., Bernards A., Borst P., Grosveld F.G. An analysis of the cosmid clones of nuclear DNA from Trypanosoma brucei shows that the genes for variant surface glycoproteins are clustered in the genome. Nucl. Acids Res. 1982;10:5903–5923. doi: 10.1093/nar/10.19.5905. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Van der Ploeg L., Bernards A., Rijsewijk F., Borst P. Characterization of the DNA duplication-transposition that controls the expression of two genes for variant surface glycoproteins in Trypanosoma brucei. Nucl. Acids Res. 1982;10:593–609. doi: 10.1093/nar/10.2.593. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Van der Ploeg L., Liu A., Michels P., Delange T., Borst P., Majumder H., Weber H., Veeneman G., Van Boom J. RNA splicing is required to make the messenger RNA for a variant surface antigen in trypanosomes. Nucl. Acids Res. 1982;10:3591–3604. doi: 10.1093/nar/10.12.3591. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Williams R., Young J., Majiwa P. Genomic environment of T. brucei VSG genes: presence of a minichromosome. Nature. 1982;299:417–421. doi: 10.1038/299417a0. [DOI] [PubMed] [Google Scholar]
  36. Young J., Donelson J., Majiwa P., Shapiro S., Williams R. Analysis of genomic rearrangements associated with two variable antigen genes of Trypanosoma brucei. Nucl. Acids Res. 1982;10:803–819. doi: 10.1093/nar/10.3.803. [DOI] [PMC free article] [PubMed] [Google Scholar]

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