LytF, a Novel Competence-Regulated Murein Hydrolase in the Genus Streptococcus
LytF, a Novel Competence-Regulated Murein Hydrolase in the Genus Streptococcus
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DOI：
10.1128/jb.06273-11
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发表时间：
2012-02-01
影响因子：
3.2
通讯作者：
Havarstein, Leiv Sigve
中科院分区：
文献类型：
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作者：
Berg, Kari Helene;Ohnstad, Hilde Solheim;Havarstein, Leiv Sigve
肺炎链球菌和可能是链球菌属的大多数其他成员都有能力进行自然遗传转化。在有能力的状态下，肺炎链球菌产生一种毛霉素水解酶CbpD，杀死并裂解无活性的肺炎球菌和密切相关的物种。先前的研究表明，在体外，CbpD对于将基因组DNA从无能力的细胞有效地转移到有能力的细胞是必不可少的。因此，有人提出，CbpD与同源免疫蛋白comm一起构成了一种DNA获取机制，使合格的肺炎球菌能够从共享同一栖息地的密切相关链球菌中捕获同源DNA。虽然编码CbpD同源物或CbpD相关蛋白的基因存在于许多不同的链球菌物种中，但许多链球菌的基因组不编码CbpD类型的蛋白。在目前的研究中，我们发现几乎所有缺乏CbpD的物种的基因组都编码了一种与能力无关的Murein水解酶，称为LytF。以戈登链球菌为模型系统，我们得到的证据表明LytF是CbpD的功能类似物。综上所述，我们的结果表明，毛霉素水解酶基因是大多数或所有链球菌的能力调节基因的一部分，表明这些溶壁酶构成了链球菌自然转化系统的重要组成部分。
Streptococcus pneumoniae and probably most other members of the genus Streptococcus are competent for natural genetic transformation. During the competent state, S. pneumoniae produces a murein hydrolase, CbpD, that kills and lyses noncompetent pneumococci and closely related species. Previous studies have shown that CbpD is essential for efficient transfer of genomic DNA from noncompetent to competent cells in vitro. Consequently, it has been proposed that CbpD together with the cognate immunity protein ComM constitutes a DNA acquisition mechanism that enables competent pneumococci to capture homologous DNA from closely related streptococci sharing the same habitat. Although genes encoding CbpD homologs or CbpD-related proteins are present in many different streptococcal species, the genomes of a number of streptococci do not encode CbpD-type proteins. In the present study we show that the genomes of nearly all species lacking CbpD encode an unrelated competence-regulated murein hydrolase termed LytF. Using Streptococcus gordonii as a model system, we obtained evidence indicating that LytF is a functional analogue of CbpD. In sum, our results show that a murein hydrolase gene is part of the competence regulon of most or all streptococcal species, demonstrating that these muralytic enzymes constitute an essential part of the streptococcal natural transformation system.