Replication of staphylococcal multiresistance plasmids
Replication of staphylococcal multiresistance plasmids
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DOI：
10.1128/jb.182.8.2170-2178.2000
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发表时间：
2000-04-01
影响因子：
3.2
通讯作者：
Skurray, RA
中科院分区：
文献类型：
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作者：
Firth, N;Apisiridej, S;Skurray, RA
基于结构和功能特性，已识别出三大类葡萄球菌多耐药质粒，即pSK1家族、psk41样共轭质粒和β -内酰胺酶重金属耐药质粒。在这里，我们描述了这些质粒群的一个代表的复制功能的分析。金黄色葡萄球菌质粒pSK1、pSK41和pI9789::Tn552的复制起始基因与木糖葡萄球菌质粒pSX267及其他革兰氏阳性属质粒的复制起始基因相关。pSK1和pI9789::Tn552之间的核苷酸序列相似性超出了它们的代表基因，分别包含上游发散转录基因orf245和orf256。我们的分析表明，编码与推断的orf245产物相关的蛋白质的基因在几种类型的组织中有不同的表现，在具有六种似乎进化上不同类型的复制起始基因的质粒上，包括theta模式和滚动圈复制子。微型复制子的构建和随后的功能分析表明，orf245是pSK1复制子分离稳定性所必需的。相比之下，在接合质粒pSK41上没有发现与orf245相当的基因，并且发现仅编码pSK41代表基因的微型复制子具有接近亲本质粒的分离稳定性。值得注意的是，研究结果表明，在临床葡萄球菌中发现的许多大的多耐药质粒，以前被认为是不相关的，实际上利用了进化相关的模复制系统。
Based on structural and functional properties, three groups of large staphylococcal multiresistance plasmids have been recognized, viz., the pSK1 family, pSK41-like conjugative plasmids, and beta-lactamase-heavy-metal resistance plasmids. Here we describe an analysis of the replication functions of a representative of each of these plasmid groups. The replication initiation genes from the Staphylococcus aureus plasmids pSK1, pSK41, and pI9789::Tn552 were found to be related to each other and to the Staphylococcus xylosus plasmid pSX267 and are also related to rep genes of several plasmids from other gram-positive genera. Nucleotide sequence similarity between pSK1 and pI9789::Tn552 extended beyond their rep genes, encompassing upstream divergently transcribed genes, orf245 and orf256, respectively. Our analyses revealed that genes encoding proteins related to the deduced orf245 product are variously represented, in several types of organization, on plasmids possessing six seemingly evolutionarily distinct types of replication initiation genes and including both theta-mode and rolling-circle replicons. Construction of minireplicons and subsequent functional analysis demonstrated that orf245 is required for the segregational stability of the pSK1 replicon. In contrast, no gene equivalent to orf245 is evident on the conjugative plasmid pSK41, and a minireplicon encoding only the pSK41 rep gene was found to exhibit a segregational stability approaching that of the parent plasmid. Significantly, the results described establish that many of the large multiresistance plasmids that have been identified in clinical staphylococci, which were formerly presumed to be unrelated, actually utilize an evolutionarily related thetamode replication system.