Enterococcus faecalis conjugative plasmid pAM373:: complete nucleotide sequence and genetic analyses of sex pheromone response
Enterococcus faecalis conjugative plasmid pAM373:: complete nucleotide sequence and genetic analyses of sex pheromone response
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DOI：
10.1046/j.1365-2958.2000.02072.x
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发表时间：
2000-09-01
影响因子：
3.6
通讯作者：
Fraser, CM
中科院分区：
文献类型：
--
作者：
De Boever, EH;Clewell, DB;Fraser, CM
pAM 373是粪肠球菌中的36.7 kb接合质粒，其编码对由肠球菌的无质粒（受体）菌株分泌的肽性信息素cAM 373的应答。15年前，它被鉴定为大肠杆菌中的五种质粒之一。粪球菌菌株RC 73，并且由于可以在金黄色葡萄球菌和戈登链球菌的培养上清液中检测到相关的信息素活性而受到关注。本文报道了pAM 373基因的全序列测定结果以及与信息素反应调控相关的关键基因的遗传分析结果。关于与接合相关的决定簇，该质粒具有与其他已知的信息素响应质粒（例如pAD 1、pCF 10和pPD 1）类似的结构组织;然而，存在几个独特的特征。虽然有显着的同源物有关的信息素结合表面蛋白（TraC）和负调节蛋白（TraA），有一个相当于pAD 1的traB（减少内源性信息素）和表面排斥蛋白的决定簇的情况下。鉴定了抑制肽iAM 373的前体结构，发现其决定簇（iam 373）位于表观转录终止子t1上游约500 nt处。Tn 917-lac插入分析提供了对信息素反应控制方面的有趣见解，并表明，尽管traA产物对信息素敏感，它的作用似乎与pAD 1的traA同源物不同。
pAM373 is a 36.7 kb conjugative plasmid in Enterococcus faecalis that encodes a response to a peptide sex pheromone, cAM373, secreted by plasmid-free (recipient) strains of enterococci. It was identified over 15 years ago as one of five plasmids in E. faecalis strain RC73 and was of interest because a related pheromone activity could be detected in culture supernatants of Staphylococcus aureus and Streptococcus gordonii, Because of increased clinical concern relating to the possibility of mobilizing vancomycin resistance determinants from enterococci, where they are becoming common, into pathogens such as S. aureus, efforts were initiated to characterize pAM373 further, The results of a complete nucleotide sequence determination of pAM373, as well as a genetic analysis of key genes related to regulation of the pheromone response, are reported here. With regard to determinants related to conjugation, the plasmid has a structural organization similar to other known pheromone-responsive plasmids such as pAD1, pCF10 and pPD1; however, there are several unique features. Although there are significant homologues relating to a pheromone-binding surface protein (TraC) and a negatively regulating protein (TraA), there is an absence of a determinant equivalent to traB of pAD1 (reduces endogenous pheromone) and a determinant for surface-exclusion protein. The precursor structure of the inhibitor peptide iAM373 was identified, and its determinant (iam373) was found to be about 500 nt upstream of an apparent transcription terminator tl, Tn917-lac insertion analyses provided interesting insights into aspects of control of the pheromone response and showed that, although the traA product is sensitive to pheromone, it appears to act differently from the traA homologue of pAD1.