The two-component system DegSU of Bacillus subtilis controls more than one hundred genes involved in several different cellular behaviours. Over the last four decades, the degU32^Hy allele, supposedly encoding a constitutively active mutant of the response regulator DegU, was exploited to define the impact of this system on cell physiology. Those studies concluded that phosphorylated DegU (DegU∼P) induced degradative enzyme expression while repressing flagellar motility and competence.

Recent experiments, however, demonstrated that flagella expression is enhanced by DegU∼P if SwrA, a protein only encoded by wild strains, is present. Yet, to promote motility, SwrA must interact with DegU∼P produced by a wild-type degU allele, as it cannot correctly cooperate with the mutant DegU32^Hy protein.

In this work, the impact of DegSU was reanalysed in the presence or absence of SwrA employing a DegS kinase mutant, degS200^Hy, to force the activation of the TCS. Our results demonstrate that the role of SwrA in B. subtilis physiology is wider than expected and affects several other DegSU targets. SwrA reduces subtilisin, cellulases and xylanases production while, besides motility, it also positively modulates competence for DNA uptake, remarkably relieving the inhibition caused by DegU∼P alone and restoring transformability in degS200^Hy strains.

枯草芽孢杆菌的双组分系统 DegSU控制着一百多个涉及几种不同细胞行为的基因。在过去的四年里，degU32 ^Hy等位基因，据称编码响应调节器 DegU 的组成型活性突变体，被用来确定该系统对细胞生理学的影响。这些研究得出结论，磷酸化的 DegU (DegU∼P) 诱导降解酶表达，同时抑制鞭毛运动和能力。

然而，最近的实验表明，如果存在仅由野生菌株编码的蛋白质 SwrA，则 DegU∼P 会增强鞭毛表达。然而，为了促进运动，SwrA 必须与野生型degU等位基因产生的 DegU∼P 相互作用，因为它不能正确地与突变的 DegU32 ^Hy蛋白配合。

在这项工作中，DegSU的影响被重新分析中的swrA采用DEGS激酶突变体，存在或不存在degS200^海兰，以迫使TCS的激活。我们的结果表明 SwrA 在B. subtilis生理学中的作用比预期的更广泛，并影响其他几个 DegSU 目标。SwrA 减少枯草杆菌蛋白酶、纤维素酶和木聚糖酶的产生，同时，除了运动性外，它还积极调节 DNA 摄取能力，显着减轻单独由 DegU∼P 引起的抑制并恢复degS200 ^Hy菌株的转化能力。