Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
Environ Microbiol. 2013 May;15(5):1387-99. doi: 10.1111/j.1462-2920.2012.02805.x. Epub 2012 Jun 12.
Vibrio cholerae inhabits aquatic environments and colonizes the human digestive tract to cause the disease cholera. In these environments, V. cholerae copes with fluctuations in salinity and osmolarity by producing and transporting small, organic, highly soluble molecules called compatible solutes, which counteract extracellular osmotic pressure. Currently, it is unclear how V. cholerae regulates the expression of genes important for the biosynthesis or transport of compatible solutes in response to changing salinity or osmolarity conditions. Through a genome-wide transcriptional analysis of the salinity response of V. cholerae, we identified a transcriptional regulator we name CosR for compatible solute regulator. The expression of cosR is regulated by ionic strength and not osmolarity. A transcriptome analysis of a ΔcosR mutant revealed that CosR represses genes involved in ectoine biosynthesis and compatible solute transport in a salinity-dependent manner. When grown in salinities similar to estuarine environments, CosR activates biofilm formation and represses motility independently of its function as an ectoine regulator. This is the first study to characterize a compatible solute regulator in V. cholerae and couples the regulation of osmotic tolerance with biofilm formation and motility.
霍乱弧菌栖息在水生环境中，并定植于人体消化道，引起霍乱病。在这些环境中，霍乱弧菌通过产生和运输小而有机、高水溶性的分子（称为相容溶质）来应对盐度和渗透压的波动，从而抵消细胞外渗透压。目前，尚不清楚霍乱弧菌如何调节与相容溶质生物合成或运输相关的基因表达，以响应盐度或渗透压条件的变化。通过对霍乱弧菌盐度反应的全基因组转录分析，我们鉴定了一个转录调节因子，我们将其命名为 CosR，即相容溶质调节因子。cosR 的表达受离子强度而不是渗透压调节。ΔcosR 突变体的转录组分析表明，CosR 以盐度依赖的方式抑制与海藻糖生物合成和相容溶质转运相关的基因。当在类似于河口环境的盐度下生长时，CosR 独立于其作为海藻糖调节剂的功能，激活生物膜形成并抑制运动。这是首次在霍乱弧菌中对相容溶质调节因子进行表征，并将渗透压耐受的调节与生物膜形成和运动联系起来。
