Campos J, Fando R, Silva A, Rodriguez B L, Benitez J A
Centro Nacional de Investigaciones, Cientificas, La Habana, Cuba.
FEMS Microbiol Lett. 1998 Jul 1;164(1):141-7. doi: 10.1111/j.1574-6968.1998.tb13079.x.
The RS1 element associated with Vibrio cholerae CTX phi prophage was cloned from an E1 Tor biotype Vibrio cholerae strain. We used the recA- vaccine strain Peru-15, that lacks the target for RS-mediated site-specific integration, to show that RS1 promotes autonomous replication of a suicide vector. A linker insertion in the rstR open reading frame abolished autonomous replication in Peru-15 but not in a strain containing an RS1 in the chromosome. An AT-rich region containing cis-acting elements involved in autonomous replication was identified by deletion. This region was sufficient to support autonomous replication in a strain containing an RS1 in the chromosome. DNA sequence analysis of a region present in RS1 and not RS2 revealed the presence of putative binding sites for host proteins involved in plasmid replication. These results indicate that RS1 contains a replicon distinct from RS2 which could be involved in replicative recombination events associated with tandem amplification of the CTX element.
与霍乱弧菌CTXφ前噬菌体相关的RS1元件是从一株埃尔托生物型霍乱弧菌菌株中克隆出来的。我们使用了recA-疫苗菌株秘鲁-15，该菌株缺乏RS介导的位点特异性整合的靶点，以证明RS1促进自杀载体的自主复制。rstR开放阅读框中的接头插入消除了秘鲁-15中的自主复制，但在染色体中含有RS1的菌株中则没有。通过缺失鉴定出一个富含AT的区域，该区域含有参与自主复制的顺式作用元件。该区域足以支持染色体中含有RS1的菌株中的自主复制。对RS1中存在而RS2中不存在的区域进行DNA序列分析，揭示了参与质粒复制的宿主蛋白的推定结合位点的存在。这些结果表明，RS1含有一个与RS2不同的复制子，它可能参与与CTX元件串联扩增相关的复制性重组事件。
