Evolution of the serum resistance-associated SRA gene in African trypanosomes

• 来源期刊: 科学通报（英文版）
• 年，卷（期）: 2009,（7）
• 页码范围: 1275-1278
• 页数: 4页
• 语种: 英文
• DOI: 10.1007/s11434-009-0137-z

摘要

Serum resistance-associated (SRA) protein, a protein unique for Trypanosoma brucei rhodesiense, is responsible for resistance of this parasite to the lysis by normal human serum (NHS) and is a vital molecular marker to distinguish this species from other African trypanosomes. We cloned and se-quenced the SRA basic copy (SRAbc) gene from T. b. rhodesiense and related species and found that this gene is confined to the subgenus Trypanozoon. The average 82% identity among the sequenced SRAbc genes indicates that they may have a common origin and are highly conserved. Since SRAbc coexists in the T. b. rhodesiense genome with SRA, we propose that SRAbc might be the 'donor VSG', which after duplication became inserted into the expression site by recombination. Under natural se-lection, SRAbc could reform into SRA following mosaic formation.