Analysis of the genetic variability of genes encoding the RNA III-activating components Agr and TRAP in a population of Staphylococcus aureus strains isolated from cows with mastitis
Analysis of the genetic variability of genes encoding the RNA III-activating components Agr and TRAP in a population of Staphylococcus aureus strains isolated from cows with mastitis
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DOI：
10.1128/jcm.40.11.4060-4067.2002
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发表时间：
2002-11-01
影响因子：
9.4
通讯作者：
Poutrel, B
中科院分区：
文献类型：
--
作者：
Gilot, P;Lina, G;Poutrel, B
金黄色葡萄球菌毒力蛋白的表达受RNA 111的控制，RNA 111是从agr基因座转录的中央多效性调节因子。RNA III由至少两个双组分系统激活，一个由agr基因座编码（AgrC-AgrA），另一个在该基因座外编码（TRAP-RAP）。在这项工作中，我们开发了新的分型方法的基础上，基因编码这两个系统，我们用来表征非克隆人口的S。金黄色葡萄球菌牛乳腺炎分离株。12个agr限制性酶切类型，在这个人口中确定，但大多数菌株（56.3%）被分组在R III-A1型。没有发现从人类分离的菌株（其agr序列可从GenBank获得）属于该主要类型。为所有这些agr变体构建的限制性图谱允许在进化方案中将所有类型联系起来，并将它们分组在四个agr干扰组之一中。这一分析表明，第2、3和4组可能是从属于第1组的更常见的类型进化而来的。agr Ⅰ群也是最普遍的（占菌株总数的69.0%）和最具多态性的干扰群。通过开发agr组特异性多重PCR，我们证实了agr干扰组中的菌株的上述分类。四个等位基因变体的陷阱也被确定，表明这两个组件系统也是多态性的。绝大多数菌株属于诱捕器Ⅰ型（71.8%）。尽管agr组和陷阱类型之间没有关系，但agr限制类型相似的菌株也具有相似的陷阱类型（除了属于agr R IV-A5和R VI-A8类型的菌株）。分析表明，S.分离自奶牛的金黄色葡萄球菌主要具有克隆结构，并且高度流行的agr R III-A1，trap I型（56.3%的菌株）可能具有赋予其上级感染牛乳腺的能力的遗传背景。
The expression of Staphylococcus aureus virulence proteins is under the control of RNA 111, a central pleiotropic regulator transcribed from the agr locus. RNA III is activated by at least two two-component systems, one encoded by the agr locus (AgrC-AgrA) and another encoded outside of this locus (TRAP-RAP). In this work, we developed new typing methods based on genes encoding these two systems, which we used to characterize a nonclonal population of S. aureus bovine mastitis isolates. Twelve agr restriction types were identified in this population, but the majority of strains (56.3%) were grouped in the R III-A1 type. No strain isolated from humans, whose agr sequence is available from GenBank, was found to belong to this major type. Restriction maps constructed for all of those agr variants allowed the linking of all types in an evolution scheme and their grouping in one of the four agr interference groups. This analysis indicates that groups 2, 3, and 4 probably evolved from the more frequently encountered type, which belongs to group 1. agr group I was also found to be the most prevalent (69.0% of the strains) and the most polymorphic interference group. By developing an agr group-specific multiplex PCR, we confirmed the above classification of strains in the agr interference groups. Four allelic variants of trap were also identified, indicating that this two-component system is also polymorphic. The majority of strains was grouped in the trap I type (71.8%,). Whereas no relationships between agr group and trap types were found, strains of similar agr restriction type were also of similar trap type (with the exception of strains belonging to the agr R IV-A5 and R VI-A8 types). Our analysis indicates that S. aureus isolated from cows has predominantly a clonal structure and that the highly prevalent agr R III-A1, trap I type (56.3% of the strains) probably possesses a genetic background which endows it with superior ability to infect the bovine mammary gland.