Characterization of a complex context containing mecA but lacking genes encoding cassette chromosome recombinases in Staphylococcus haemolyticus.
Characterization of a complex context containing mecA but lacking genes encoding cassette chromosome recombinases in Staphylococcus haemolyticus.
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DOI：
10.1186/1471-2180-13-64
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发表时间：
2013-03-22
期刊：
影响因子：
4.2
通讯作者：
Zong Z
中科院分区：
文献类型：
--
作者：
Zong Z
甲氧西林耐药决定簇mecA通常通过SCCmec元件转移。然而，溶血葡萄球菌临床分离株WCH 1中的SCCmec可能不携带mecA基因，因为未检测到盒式染色体重组酶基因。因此，研究了WCH 1中mecA的遗传背景。从WCH 1中获得了一个40-kb的含有mecA的区域，其一端由orfX和S的几个orfs连接。另一条是溶血性弧菌的核心染色体。这个40 kb的区域在结构上非常复杂，具有多个似乎具有不同起源的遗传组分。例如，与orfX相邻的3.7kb结构与表皮葡萄球菌RP 62 a染色体上的结构几乎相同，但在S.溶血性链球菌JCSC 1435。发现SCC的末端反向重复序列，但未检测到ccr基因。mecA被两个拷贝的IS 431包围，IS 431的侧翼是8-bp的直接靶重复序列（DR）。8bp DR的存在表明IS 431的两个拷贝可能形成了用于动员mecA的复合转座子。这一发现具有重要意义，因为IS 431的多个拷贝通常存在于mecA的环境中，这可能具有形成各种复合转座子的潜力，这些复合转座子可以介导mecA的动员。本研究还解释了一些携带mecA的葡萄球菌分离株中不存在ccr的原因。
Methicillin resistance determinant mecA is generally transferred by SCCmec elements. However, the mecA gene might not be carried by a SCCmec in a Staphylococcus haemolyticus clinical isolate, WCH1, as no cassette chromosome recombinase genes were detected. Therefore, the genetic context of mecA in WCH1 was investigated. A 40-kb region containing mecA was obtained from WCH1, bounded by orfX at one end and several orfs of S. haemolyticus core chromosome at the other. This 40-kb region was very complex in structure with multiple genetic components that appeared to have different origins. For instance, the 3.7-kb structure adjacent to orfX was almost identical to that on the chromosome of Staphylococcus epidermidis RP62a but was absent from S. haemolyticus JCSC1435. Terminal inverted repeats of SCC were found but no ccr genes could be detected. mecA was bracketed by two copies of IS431, which was flanked by 8-bp direct target repeat sequence (DR). The presence of 8-bp DR suggests that the two copies of IS431 might have formed a composite transposon for mobilizing mecA. This finding is of significance as multiple copies of IS431 are commonly present in the contexts of mecA, which might have the potential to form various composite transposons that could mediate the mobilization of mecA. This study also provides an explanation for the absence of ccr in some staphylococci isolates carrying mecA.
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影响因子：
3.2
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