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Gene conversion as a mechanism for antigenic variation in trypanosomes
Cell
|September 1, 1983
Summary
Trypanosome surface antigen gene expression involves gene duplication and conversion. Different gene family members contribute to diverse antigen repertoires, impacting serological detection.
Area of Science:
- Molecular Biology
- Parasitology
- Genetics
Background:
- The expression of trypanosome surface antigen genes, such as AnTat 1.1, is regulated by gene transposition to active expression sites.
- Understanding the mechanisms behind generating diverse surface antigen repertoires is crucial for comprehending parasite immune evasion strategies.
Purpose of the Study:
- To investigate the molecular mechanisms underlying the generation of new surface antigen genes in trypanosome clones AnTat 1.10 and AnTat 1.1B.
- To elucidate the role of gene conversion in transforming transposed gene elements and diversifying the antigen repertoire.
Main Methods:
- Analysis of genomic rearrangements in trypanosome clones AnTat 1.10 and AnTat 1.1B derived from AnTat 1.1.
- Comparison of resultant messenger RNA (mRNA) sequences (AnTat 1.1, 1.10, and 1.1B) for homology and differences.
- Serological techniques to assess the distinguishability of surface coats coded by different antigen variants.
Main Results:
- Evidence of gene conversion in the transformation of the AnTat 1.1 transposed element into AnTat 1.10 and AnTat 1.1B sequences.
- The three mRNAs share significant homology, but AnTat 1.10 codes for a serologically distinct surface coat compared to AnTat 1.1 and AnTat 1.1B.
- Genomic rearrangements involve two members of the AnTat 1.1 gene family located in unstable telomeric regions.
Conclusions:
- Duplicative transposition of trypanosome surface antigen genes is mediated by gene conversion, potentially involving variable lengths of silent genes.
- Different members of the same gene family can contribute to the diversification of the surface antigen repertoire, influencing parasite antigenicity.
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