Identification of the gene encoding the alternative sigma factor σB from Listeria monocytogenes and its role in osmotolerance
Identification of the gene encoding the alternative sigma factor σB from Listeria monocytogenes and its role in osmotolerance
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DOI：
10.1128/jb.180.17.4547-4554.1998
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发表时间：
1998-09-01
影响因子：
3.2
通讯作者：
Benson, AK
中科院分区：
文献类型：
--
作者：
Becker, LA;Çetin, MS;Benson, AK
单核细胞增生李斯特菌（Listeria monocytogenes）是一种生理活性很强的细菌，可以在低温、高渗透压和低pH条件下生长。虽然单核细胞增多症的发病率降低，以减轻这些不利环境的生理后果，很少有人知道这些反应是如何协调的。在这里提出的研究中，我们已经克隆了sigB基因和几个rsb基因，从单核细胞增生李斯特菌，编码同源物的替代西格玛因子西格玛（B）和RsbUVWX蛋白，其管理转录的一般应力调节子在相关的细菌枯草芽孢杆菌。洛杉矶单核细胞增多症李斯特菌和B、枯草杆菌sigB和rsb基因在序列和物理组织上相似;然而，我们观察到，sigma（B）在单核细胞增多症李斯特菌中的活性独特地响应于渗透上移、温度下移和生长培养基中EDTA的存在。在渗透压升高后，响应的幅度最大，表明σ（B）在协调L. sigB基因的无效突变导致单核细胞增生性李斯特菌的能力显著缺陷。单核细胞增生症使用甜菜碱和肉毒碱作为细胞保护剂。随后对甜菜碱转运的测量证实，σ（B）的缺乏降低了细胞积累甜菜碱的能力。因此，σ（B）协调对各种物理和化学信号的响应，并且其功能促进单核细胞增生李斯特菌在高渗透强度条件下的生长。
Listeria monocytogenes is well known for its robust physiology, which permits growth at low temperatures under conditions of high osmolarity and low pH, Although studies have provided insight into the mechanisms used by L. monocytogenes to allay the physiological consequences of these adverse environments, little is known about how these responses are coordinated. In the studies presented here, we have cloned the sigB gene and several rsb genes from L, monocytogenes, encoding homologs of the alternative sigma factor sigma(B) and the RsbUVWX proteins, which govern transcription of a general stress regulon in the related bacterium Bacillus subtilis. The L. monocytogenes and B, subtilis sigB and rsb genes are similar in sequence and physical organization; however, we observed that the activity of sigma(B) in L, monocytogenes was uniquely responsive to osmotic upshifting, temperature downshifting, and the presence of EDTA in the growth medium. The magnitude of the response was greatest after an osmotic upshift, suggesting a role for sigma(B) in coordinating osmotic responses in L. monocytogenes, A null mutation in the sigB gene led to substantial defects in the ability of L. monocytogenes to use betaine and carnitine as osmoprotectants. Subsequent measurements of betaine transport confirmed that the absence of sigma(B) reduced the ability of the cells to accumulate betaine, Thus, sigma(B) coordinates responses to a variety of physical and chemical signals, and its function facilitates the growth of L, monocytogenes under conditions of high osmotic strength.