Pays E, Houard S, Pays A, Van Assel S, Dupont F, Aerts D, Huet-Duvillier G, Gomés V, Richet C, Degand P
Cell. 1985 Oct;42(3):821-9. doi: 10.1016/0092-8674(85)90278-8.
The boundaries of gene conversion in variant-specific antigen genes have been determined in six clones of Trypanosoma brucei. In each clone, antigenic switching involved interaction between two telomeric members of the AnTat 1.1 multigene family, which share extensive homology throughout their coding regions. All conversion events occurred by substitution of faithful copies of donor sequences. Conversion endpoints were nonrandomly distributed. In four clones, the 5' conversion limit was near the antigen translation initiation codon, while in three clones, the 3' conversion limit was located at the "hinge" between the two major antigen domains. In one case, two segmental conversions were involved in antigen switching. These observations reveal that antigen gene conversion can occur without generating point mutations, and suggest that postrecombinational selection may impose a limit on the number of possible rearrangements within antigen genes.
已经在布氏锥虫的六个克隆中确定了变异特异性抗原基因中基因转换的边界。在每个克隆中，抗原转换涉及AnTat 1.1多基因家族的两个端粒成员之间的相互作用，这两个成员在其整个编码区域具有广泛的同源性。所有转换事件都是通过供体序列的忠实拷贝替换发生的。转换终点是非随机分布的。在四个克隆中，5'转换极限靠近抗原翻译起始密码子，而在三个克隆中，3'转换极限位于两个主要抗原结构域之间的“铰链”处。在一个案例中，两次片段转换参与了抗原转换。这些观察结果表明，抗原基因转换可以在不产生点突变的情况下发生，并表明重组后选择可能对抗原基因内可能的重排数量施加限制。
