Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
Mol Microbiol. 2013 Jun;88(5):984-97. doi: 10.1111/mmi.12235. Epub 2013 May 7.
Biofilm formation in Bacillus subtilis requires expression of the eps and tapA-sipW-tasA operons to synthesize the extracellular matrix components, extracellular polysaccharide and TasA amyloid proteins, respectively. Expression of both operons is inhibited by the DNA-binding protein master regulator of biofilm formation SinR and activated by the protein RemA. Here we show that RemA is a DNA-binding protein that binds to multiple sites upstream of the promoters of both operons and is both necessary and sufficient for transcriptional activation in vivo and in vitro. We further show that SinR negatively regulates eps operon expression by occluding RemA binding and thus for the P(eps) promoter SinR functions as an anti-activator. Finally, transcriptional profiling indicated that RemA was primarily a regulator of the extracellular matrix genes, but it also activated genes involved in osmoprotection, leading to the identification of another direct target, the opuA operon.
枯草芽孢杆菌生物膜的形成需要表达 eps 和 tapA-sipW-tasA 操纵子，分别合成细胞外基质成分——胞外多糖和 TasA 淀粉样蛋白。这两个操纵子的表达都受到生物膜形成的 DNA 结合蛋白主调控因子 SinR 的抑制，并被蛋白 RemA 激活。在这里，我们表明 RemA 是一种 DNA 结合蛋白，它可以结合到两个操纵子启动子上游的多个位点，并且是体内和体外转录激活所必需和充分的。我们进一步表明，SinR 通过阻断 RemA 结合来负调控 eps 操纵子的表达，因此对于 P(eps)启动子，SinR 作为一种反激活因子发挥作用。最后，转录谱分析表明，RemA 主要是细胞外基质基因的调控因子，但它也激活了参与渗透压保护的基因，导致另一个直接靶点 opuA 操纵子的鉴定。
