Clostridium difficile Has Two Parallel and Essential Sec Secretion Systems
Clostridium difficile Has Two Parallel and Essential Sec Secretion Systems
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DOI：
10.1074/jbc.m111.263889
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发表时间：
2011-08-05
影响因子：
4.8
通讯作者：
Fairweather, Neil F.
中科院分区：
文献类型：
--
作者：
Fagan, Robert P.;Fairweather, Neil F.
蛋白质跨细胞质膜转运是所有细菌的基本过程。Sec系统在其核心处包括ATP酶SecA和膜通道SecYEG，负责大部分这种蛋白质转运。最近，第二个平行的SEC系统已被描述在一些革兰氏阳性的物种。该辅助Sec系统的特征在于存在供能ATP酶SecA 2的第二拷贝;在已经研究的情况下，SecA 2负责Sec底物的子集的易位。与许多致病性革兰氏阳性菌种一样，艰难梭菌具有两个SecA拷贝。在这里，我们描述了C的第一个特征。difficile辅助Sec系统及其主要底物的鉴定。使用可诱导的反义RNA表达和显性负等位基因的secA 1和secA 2，我们表明，出口的S-层蛋白（SLP）和一个额外的细胞壁蛋白（CwpV）是依赖于SecA 2。在表达显性阴性secA 1或secA 2等位基因的细胞中观察到SLP SlpA和其他细胞壁蛋白质的细胞质前体的积累，伴随着细胞壁中成熟SLP水平的降低。此外，显性负性等位基因的表达或SecA 1或SecA 2的反义RNA敲低显著损害生长，表明这两个Sec系统在C.很难
Protein translocation across the cytoplasmic membrane is an essential process in all bacteria. The Sec system, comprising at its core an ATPase, SecA, and a membrane channel, SecYEG, is responsible for the majority of this protein transport. Recently, a second parallel Sec system has been described in a number of Gram-positive species. This accessory Sec system is characterized by the presence of a second copy of the energizing ATPase, SecA2; where it has been studied, SecA2 is responsible for the translocation of a subset of Sec substrates. In common with many pathogenic Gram-positive species, Clostridium difficile possesses two copies of SecA. Here, we describe the first characterization of the C. difficile accessory Sec system and the identification of its major substrates. Using inducible antisense RNA expression and dominant-negative alleles of secA1 and secA2, we demonstrate that export of the S-layer proteins (SLPs) and an additional cell wall protein (CwpV) is dependent on SecA2. Accumulation of the cytoplasmic precursor of the SLPs SlpA and other cell wall proteins was observed in cells expressing dominant-negative secA1 or secA2 alleles, concomitant with a decrease in the levels of mature SLPs in the cell wall. Furthermore, expression of either dominant-negative allele or antisense RNA knockdown of SecA1 or SecA2 dramatically impaired growth, indicating that both Sec systems are essential in C. difficile.