Abstract
We previously described a bloodstream Trypansoma rhodesiense clone, MVAT5-Rx2, whose isolation was based on its cross-reactivity with a monoclonal antibody (MAb) directed against a metacyclic variant surface glycoprotein (VSG). When the duplicated, expressed VSG gene in MVAT5-Rx2 was compared with its donor (basic copy) gene, 11 nucleotide differences were found in the respective 1.5-kb coding regions (Y. Lu, T. Hall, L. S. Gay, and J. E. Donelson, Cell 72:397-406, 1993). Here we describe a characterization of two additional bloodstream trypanosome clones, MVAT5-Rx1 and MVAT5-Rx3, whose VSGs are expressed from duplicated copies of the same donor VSG gene. The three trypanosome clones each react with the MVAT5-specific MAb, but they have different cross-reactivities with a panel of other MAbs, suggesting that their surface epitopes are similar but nonidentical. Each of the three gene duplication events occurs at a different 5' crossover site within a 76-bp repeat and is associated with a different set of point mutations. The 35, 11, and 28 point mutations in the duplicated VSG coding regions of Rx1, Rx2, and Rx3, respectively, exhibit a strand bias. In the sense strand, of the 74 total mutations generated in the three duplications, 54% are A-to-G or G-to-A (A:G) transitions and 7% are C:T transitions, while 26% are C:A transversions and 13% are C:G transversions. No T:G or T:A transversions occurred. Possible models for the generation of these point mutations are discussed.
Full text
PDF









Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Barbet A. F., Kamper S. M. The importance of mosaic genes to trypanosome survival. Parasitol Today. 1993 Feb;9(2):63–66. doi: 10.1016/0169-4758(93)90039-i. [DOI] [PubMed] [Google Scholar]
- Bernards A., van Harten-Loosbroek N., Borst P. Modification of telomeric DNA in Trypanosoma brucei; a role in antigenic variation? Nucleic Acids Res. 1984 May 25;12(10):4153–4170. doi: 10.1093/nar/12.10.4153. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Blackburn E. H., Challoner P. B. Identification of a telomeric DNA sequence in Trypanosoma brucei. Cell. 1984 Feb;36(2):447–457. doi: 10.1016/0092-8674(84)90238-1. [DOI] [PubMed] [Google Scholar]
- Blum M. L., Down J. A., Gurnett A. M., Carrington M., Turner M. J., Wiley D. C. A structural motif in the variant surface glycoproteins of Trypanosoma brucei. Nature. 1993 Apr 15;362(6421):603–609. doi: 10.1038/362603a0. [DOI] [PubMed] [Google Scholar]
- Borst P. Discontinuous transcription and antigenic variation in trypanosomes. Annu Rev Biochem. 1986;55:701–732. doi: 10.1146/annurev.bi.55.070186.003413. [DOI] [PubMed] [Google Scholar]
- Campbell D. A., van Bree M. P., Boothroyd J. C. The 5'-limit of transposition and upstream barren region of a trypanosome VSG gene: tandem 76 base-pair repeats flanking (TAA)90. Nucleic Acids Res. 1984 Mar 26;12(6):2759–2774. doi: 10.1093/nar/12.6.2759. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Campbell G. H., Esser K. M., Wellde B. T., Diggs C. L. Isolation and characterization of a new serodeme of Trypanosoma rhodesiense. Am J Trop Med Hyg. 1979 Nov;28(6):974–983. doi: 10.4269/ajtmh.1979.28.974. [DOI] [PubMed] [Google Scholar]
- Crowe J. S., Barry J. D., Luckins A. G., Ross C. A., Vickerman K. All metacyclic variable antigen types of Trypanosoma congolense identified using monoclonal antibodies. Nature. 1983 Nov 24;306(5941):389–391. doi: 10.1038/306389a0. [DOI] [PubMed] [Google Scholar]
- Donelson J. E., Rice-Ficht A. C. Molecular biology of trypanosome antigenic variation. Microbiol Rev. 1985 Jun;49(2):107–125. doi: 10.1128/mr.49.2.107-125.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dorfman D. M., Donelson J. E. Characterization of the 1.35 kilobase DNA repeat unit containing the conserved 35 nucleotides at the 5'-termini of variable surface glycoprotein mRNAs in Trypanosoma brucei. Nucleic Acids Res. 1984 Jun 25;12(12):4907–4920. doi: 10.1093/nar/12.12.4907. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Esser K. M., Schoenbechler M. J., Gingrich J. B. Trypanosoma rhodesiense blood forms express all antigen specificities relevant to protection against metacyclic (insect form) challenge. J Immunol. 1982 Oct;129(4):1715–1718. [PubMed] [Google Scholar]
- Gommers-Ampt J., Lutgerink J., Borst P. A novel DNA nucleotide in Trypanosoma brucei only present in the mammalian phase of the life-cycle. Nucleic Acids Res. 1991 Apr 25;19(8):1745–1751. doi: 10.1093/nar/19.8.1745. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hattori M., Sakaki Y. Dideoxy sequencing method using denatured plasmid templates. Anal Biochem. 1986 Feb 1;152(2):232–238. doi: 10.1016/0003-2697(86)90403-3. [DOI] [PubMed] [Google Scholar]
- Kamper S. M., Barbet A. F. Surface epitope variation via mosaic gene formation is potential key to long-term survival of Trypanosoma brucei. Mol Biochem Parasitol. 1992 Jul;53(1-2):33–44. doi: 10.1016/0166-6851(92)90004-4. [DOI] [PubMed] [Google Scholar]
- Kearney J. F., Radbruch A., Liesegang B., Rajewsky K. A new mouse myeloma cell line that has lost immunoglobulin expression but permits the construction of antibody-secreting hybrid cell lines. J Immunol. 1979 Oct;123(4):1548–1550. [PubMed] [Google Scholar]
- Köhler G., Milstein C. Continuous cultures of fused cells secreting antibody of predefined specificity. Nature. 1975 Aug 7;256(5517):495–497. doi: 10.1038/256495a0. [DOI] [PubMed] [Google Scholar]
- Lenardo M. J., Rice-Ficht A. C., Kelly G., Esser K. M., Donelson J. E. Characterization of the genes specifying two metacyclic variable antigen types in Trypanosoma brucei rhodesiense. Proc Natl Acad Sci U S A. 1984 Nov;81(21):6642–6646. doi: 10.1073/pnas.81.21.6642. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lommel L., Hanawalt P. C. Increased UV resistance of a xeroderma pigmentosum revertant cell line is correlated with selective repair of the transcribed strand of an expressed gene. Mol Cell Biol. 1993 Feb;13(2):970–976. doi: 10.1128/mcb.13.2.970. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lu Y., Hall T., Gay L. S., Donelson J. E. Point mutations are associated with a gene duplication leading to the bloodstream reexpression of a trypanosome metacyclic VSG. Cell. 1993 Feb 12;72(3):397–406. doi: 10.1016/0092-8674(93)90116-8. [DOI] [PubMed] [Google Scholar]
- Pays E., Delauw M. F., Laurent M., Steinert M. Possible DNA modification in GC dinucleotides of Trypanosoma brucei telomeric sequences; relationship with antigen gene transcription. Nucleic Acids Res. 1984 Jul 11;12(13):5235–5247. doi: 10.1093/nar/12.13.5235. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pays E., Guyaux M., Aerts D., Van Meirvenne N., Steinert M. Telomeric reciprocal recombination as a possible mechanism for antigenic variation in trypanosomes. Nature. 1985 Aug 8;316(6028):562–564. doi: 10.1038/316562a0. [DOI] [PubMed] [Google Scholar]
- Pays E., Van Assel S., Laurent M., Darville M., Vervoort T., Van Meirvenne N., Steinert M. Gene conversion as a mechanism for antigenic variation in trypanosomes. Cell. 1983 Sep;34(2):371–381. doi: 10.1016/0092-8674(83)90371-9. [DOI] [PubMed] [Google Scholar]
- Radding C. M. Genetic recombination: strand transfer and mismatch repair. Annu Rev Biochem. 1978;47:847–880. doi: 10.1146/annurev.bi.47.070178.004215. [DOI] [PubMed] [Google Scholar]
- Rice-Ficht A. C., Chen K. K., Donelson J. E. Point mutations during generation of expression-linked extra copy of trypanosome surface glycoprotein gene. Nature. 1982 Aug 12;298(5875):676–679. doi: 10.1038/298676a0. [DOI] [PubMed] [Google Scholar]
- Roth C., Bringaud F., Layden R. E., Baltz T., Eisen H. Active late-appearing variable surface antigen genes in Trypanosoma equiperdum are constructed entirely from pseudogenes. Proc Natl Acad Sci U S A. 1989 Dec;86(23):9375–9379. doi: 10.1073/pnas.86.23.9375. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rudenko G., Bishop D., Gottesdiener K., Van der Ploeg L. H. Alpha-amanitin resistant transcription of protein coding genes in insect and bloodstream form Trypanosoma brucei. EMBO J. 1989 Dec 20;8(13):4259–4263. doi: 10.1002/j.1460-2075.1989.tb08611.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Selby C. P., Sancar A. Molecular mechanism of transcription-repair coupling. Science. 1993 Apr 2;260(5104):53–58. doi: 10.1126/science.8465200. [DOI] [PubMed] [Google Scholar]
- Shah J. S., Young J. R., Kimmel B. E., Iams K. P., Williams R. O. The 5' flanking sequence of a Trypanosoma brucei variable surface glycoprotein gene. Mol Biochem Parasitol. 1987 Jun;24(2):163–174. doi: 10.1016/0166-6851(87)90103-4. [DOI] [PubMed] [Google Scholar]
- Thon G., Baltz T., Eisen H. Antigenic diversity by the recombination of pseudogenes. Genes Dev. 1989 Aug;3(8):1247–1254. doi: 10.1101/gad.3.8.1247. [DOI] [PubMed] [Google Scholar]
- Turner C. M., Barry J. D. High frequency of antigenic variation in Trypanosoma brucei rhodesiense infections. Parasitology. 1989 Aug;99(Pt 1):67–75. doi: 10.1017/s0031182000061035. [DOI] [PubMed] [Google Scholar]
- Turner C. M., Barry J. D., Maudlin I., Vickerman K. An estimate of the size of the metacyclic variable antigen repertoire of Trypanosoma brucei rhodesiense. Parasitology. 1988 Oct;97(Pt 2):269–276. doi: 10.1017/s0031182000058479. [DOI] [PubMed] [Google Scholar]
- Turner M. J. The biochemistry of the surface antigens of the African trypanosomes. Br Med Bull. 1985 Apr;41(2):137–143. doi: 10.1093/oxfordjournals.bmb.a072040. [DOI] [PubMed] [Google Scholar]
- Van der Ploeg L. H. Control of antigenic variation in African trypanosomes. New Biol. 1991 Apr;3(4):324–330. [PubMed] [Google Scholar]
- Van der Ploeg L. H., Valerio D., De Lange T., Bernards A., Borst P., Grosveld F. G. An analysis of cosmid clones of nuclear DNA from Trypanosoma brucei shows that the genes for variant surface glycoproteins are clustered in the genome. Nucleic Acids Res. 1982 Oct 11;10(19):5905–5923. doi: 10.1093/nar/10.19.5905. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Veaute X., Fuchs R. P. Greater susceptibility to mutations in lagging strand of DNA replication in Escherichia coli than in leading strand. Science. 1993 Jul 30;261(5121):598–600. doi: 10.1126/science.8342022. [DOI] [PubMed] [Google Scholar]
- Wiley D. C., Skehel J. J. The structure and function of the hemagglutinin membrane glycoprotein of influenza virus. Annu Rev Biochem. 1987;56:365–394. doi: 10.1146/annurev.bi.56.070187.002053. [DOI] [PubMed] [Google Scholar]