Pilin and Sortase Residues Critical for Endocarditis- and BiofilmAssociated Pilus Biogenesis in Enterococcus faecalis
Pilin and Sortase Residues Critical for Endocarditis- and BiofilmAssociated Pilus Biogenesis in Enterococcus faecalis
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DOI：
10.1128/jb.00451-13
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发表时间：
2013-10-01
影响因子：
3.2
通讯作者：
Hultgren, Scott J.
中科院分区：
文献类型：
--
作者：
Nielsen, Hailyn V.;Flores-Mireles, Ana L.;Hultgren, Scott J.
肠球菌通常引起医院获得性感染，如感染性心内膜炎和导管相关性尿路感染。在这些感染的动物模型中，被称为心内膜炎和生物膜相关（Ebp）菌毛的长毛样细胞外蛋白纤维是粪肠球菌的重要毒力因子。对于Ebp和其他分选酶组装的皮利，菌毛相关分选酶对于纤维形成是必需的，因为它们在分选酶识别基序和菌毛亚基的菌毛蛋白样基序之间产生共价异肽键。然而，控制三个菌毛亚基（EbpA、EbpB和EbpC）掺入的分子要求尚未在E.粪便。在这里，我们表明，在EbpC亚基的菌毛蛋白样基序内的赖氨酸残基是必要的EbpC聚合。然而，EbpA掺入菌毛纤维只需要其分选酶识别基序（LPXTG），而EbpB的掺入只需要其菌毛蛋白样基序。菌毛尖端亚基的掺入仅需要分选酶识别基序，而基础亚基的掺入仅需要菌毛蛋白识别基序。因此，这些数据支持在EbpC聚合物的尖端处具有EbpA且在基部处具有EbpB的模型。此外，管家分选酶，SrtA，被发现处理EbpB和其预测的催化Cys残基所需的成熟Ebp皮利的有效细胞壁锚定。因此，我们已经确定了在纤维聚合，次要亚基组织，菌毛亚细胞区室化在大肠杆菌的分子相互作用。粪肠Ebp菌毛系统这些研究推进了我们对分选酶组装菌毛生物发生的独特分子机制的理解。
Enterococci commonly cause hospital-acquired infections, such as infective endocarditis and catheter-associated urinary tract infections. In animal models of these infections, a long hairlike extracellular protein fiber known as the endocarditis-and biofilm-associated (Ebp) pilus is an important virulence factor for Enterococcus faecalis. For Ebp and other sortase-assembled pili, the pilus-associated sortases are essential for fiber formation as they create covalent isopeptide bonds between the sortase recognition motif and the pilin-like motif of the pilus subunits. However, the molecular requirements governing the incorporation of the three pilus subunits (EbpA, EbpB, and EbpC) have not been investigated in E. faecalis. Here, we show that a Lys residue within the pilin-like motif of the EbpC subunit was necessary for EbpC polymerization. However, incorporation of EbpA into the pilus fiber only required its sortase recognition motif (LPXTG), while incorporation of EbpB only required its pilin-like motif. Only the sortase recognition motif would be required for incorporation of the pilus tip subunit, while incorporation of the base subunit would only require the pilin recognition motif. Thus, these data support a model with EbpA at the tip and EbpB at the base of an EbpC polymer. In addition, the housekeeping sortase, SrtA, was found to process EbpB and its predicted catalytic Cys residue was required for efficient cell wall anchoring of mature Ebp pili. Thus, we have defined molecular interactions involved in fiber polymerization, minor subunit organization, and pilus subcellular compartmentalization in the E. faecalis Ebp pilus system. These studies advance our understanding of unique molecular mechanisms of sortase-assembled pilus biogenesis.