Novel type v staphylococcal cassette chromosome mec driven by a novel cassette chromosome recombinase, ccrC
Novel type v staphylococcal cassette chromosome mec driven by a novel cassette chromosome recombinase, ccrC
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DOI：
10.1128/aac.48.7.2637-2651.2004
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发表时间：
2004-07-01
影响因子：
4.9
通讯作者：
Hiramatsu, K
中科院分区：
文献类型：
--
作者：
Ito, T;Ma, XX;Hiramatsu, K
葡萄球菌盒式染色体mec(Sccmec)是由编码甲氧西林耐药的mec基因复合体和编码决定其迁移性的重组酶组成的ccr基因复合体组成的可移动的遗传元件。Mec基因复合体分为四类，CCR基因复合体分为三种同种异型。到目前为止，mEC基因复合体类别和CCR基因复合体类型的不同组合定义了四种类型的SCCmec元件。现在，我们介绍在澳大利亚分离的耐甲氧西林金黄色葡萄球菌(菌株Wis[WBG8318])的染色体上发现的第五种SCCmec同种异型。该元件与现存的四种类型的SCCmec具有相同的染色体整合位点和染色体-SCCmec连接区的特征核苷酸序列。新的SCCmec携带由IS431(IS431-mecA-DelTamecR1-IS431)包围的mecA，被命名为C2 mec基因复合体；它携带的不是CCRA和CCRB基因，而是编码盒染色体重组酶的基因同源物的单一拷贝。由于开放阅读框架(ORF)被发现编码一种酶，催化该元件的精确切割以及定点和定向整合，我们将其命名为ORF盒染色体重组酶C(CCRC)，我们将其命名为VSCCmec元件。V型SCCmec是一个小的SCCmec元件(28kb)，除mecA外，不携带任何抗生素耐药基因。与现存的SCCmec类型不同，它携带一组外来基因，编码一种限制修饰系统，可能在稳定染色体上的元件方面发挥作用。
Staphylococcal cassette chromosome mec (SCCmec) is a mobile genetic element composed of the mec gene complex, which encodes methicillin resistance, and the ccr gene complex, which encodes the recombinases responsible for its mobility. The mec gene complex has been classified into four classes, and the ccr gene complex has been classified into three allotypes. Different combinations of mec gene complex classes and ccr gene complex types have so far defined four types of SCCmec elements. Now we introduce the fifth allotype of SCCmec, which was found on the chromosome of a community-acquired methicillin-resistant Staphylococcus aureus strain (strain WIS [WBG8318]) isolated in Australia. The element shared the same chromosomal integration site with the four extant types of SCCmec and the characteristic nucleotide sequences at the chromosome-SCCmec junction regions. The novel SCCmec carried mecA bracketed by IS431 (IS431-mecA-DeltamecR1-IS431), which is designated the class C2 mec gene complex; and instead of ccrA and ccrB genes, it carried a single copy of a gene homologue that encoded cassette chromosome recombinase. Since the open reading frame (ORF) was found to encode an enzyme which catalyzes the precise excision as well as site- and orientation-specific integration of the element, we designated the ORF cassette chromosome recombinase C (ccrC), and we designated the element type V SCCmec. Type V SCCmec is a small SCCmec element (28 kb) and does not carry any antibiotic resistance genes besides mecA. Unlike the extant SCCmec types, it carries a set of foreign genes encoding a restriction-modification system that might play a role in the stabilization of the element on the chromosome.