Hobbs M R, Boothroyd J C
Department of Microbiology and Immunology, Stanford University CA 94305-5402.
Mol Biochem Parasitol. 1990 Nov;43(1):1-16. doi: 10.1016/0166-6851(90)90125-6.
Utilizing first-strand cDNA from different stages, a gene family was identified that is expressed in bloodstream form trypanosomes but not in cultured procyclic forms. This family of 50-100 genes, termed bloodstream-specific 1 (BS1), shares a chromosomal distribution pattern similar to the variant surface glycoprotein (VSG) genes and the expression-site-associated genes (ESAGs). The BS1 genes are expressed in several variants of Trypanosoma brucei brucei and in Trypanosoma brucei gambiense. Sequence analysis of five members of this gene family reveals the recently described ESAG 6 and ESAG 7 genes as well as the ESAG X gene to be members of this family. We have been unable to localize the BS1 gene product in the cell but show that chronically infected rabbit serum recognizes recombinant BS1 protein arguing for expression in vivo. Finally we note that the derived protein sequence for the BS1 genes suggests an evolutionary relationship with at least one variant surface glycoprotein gene, and hence these studies may provide clues to understanding the molecular origins of antigenic variation in trypanosomes.
利用来自不同阶段的第一链cDNA，鉴定出一个基因家族，该家族在血流形式的锥虫中表达，但在培养的前循环形式中不表达。这个由50 - 100个基因组成的家族，称为血流特异性1（BS1），其染色体分布模式与可变表面糖蛋白（VSG）基因和表达位点相关基因（ESAGs）相似。BS1基因在布氏布氏锥虫的几个变体以及布氏冈比亚锥虫中表达。对该基因家族的五个成员进行序列分析发现，最近描述的ESAG 6和ESAG 7基因以及ESAG X基因是这个家族的成员。我们无法在细胞中定位BS1基因产物，但表明慢性感染兔血清能识别重组BS1蛋白，这表明该蛋白在体内有表达。最后，我们注意到BS1基因的推导蛋白序列表明它与至少一个可变表面糖蛋白基因存在进化关系，因此这些研究可能为理解锥虫抗原变异的分子起源提供线索。
