Shyamala V, Schneider E, Ames G F
Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720.
EMBO J. 1990 Mar;9(3):939-46. doi: 10.1002/j.1460-2075.1990.tb08192.x.
We show that a family of prokaryotic repetitive sequences, called REP (repetitive extragenic palindromic), (Stern et al., 1984) is involved in the formation of chromosomal rearrangements such as duplications. The join-points of seven RecA+ tandem duplications previously characterized in Salmonella typhimurium, that fuse the hisD gene to distant foreign promoters, were cloned and sequenced. In all seven cases they are shown to have originated by recombination between distant REP sequences. Importantly, several join-points had also occurred at REP sequences even in a RecA-background. Thus, REPs can recombine with each other by a RecA(-)-independent mechanism involved in the generation of chromosomal rearrangements. While all RecA+ duplications analysed resulted from recombination between REP sequences, some RecA-duplications did occur also outside of REP sequences, in one case by recombination within a 7 bp homology. Possible roles for the known interaction between DNA gyrase and REP in chromosomal rearrangements are discussed.
我们发现，一类名为REP（重复基因外回文序列）的原核重复序列（Stern等人，1984年）参与了染色体重排（如重复）的形成。之前在鼠伤寒沙门氏菌中鉴定出的七个RecA+串联重复序列的连接点，这些连接点将hisD基因与远处的外源启动子融合，已被克隆并测序。在所有七个案例中，它们都显示是由远处REP序列之间的重组产生的。重要的是，即使在RecA背景下，一些连接点也出现在REP序列处。因此，REP可以通过一种不依赖RecA的机制相互重组，这种机制参与染色体重排的产生。虽然分析的所有RecA+重复序列都是由REP序列之间的重组产生的，但一些RecA-重复序列也确实发生在REP序列之外，在一个案例中是通过7bp同源序列内的重组产生的。文中还讨论了DNA促旋酶与REP之间已知的相互作用在染色体重排中的可能作用。
