Pannen Derk, Fabisch Maria, Gausling Lisa, Schnetz Karin
From the Institute for Genetics, University of Cologne, Zülpicher Strasse 47a, 50674 Cologne, Germany.
From the Institute for Genetics, University of Cologne, Zülpicher Strasse 47a, 50674 Cologne, Germany
J Biol Chem. 2016 Jan 29;291(5):2357-70. doi: 10.1074/jbc.M115.696815. Epub 2015 Dec 3.
The Rcs phosphorelay is a two-component signal transduction system that is induced by cell envelope stress. RcsB, the response regulator of this signaling system, is a pleiotropic transcription regulator, which is involved in the control of various stress responses, cell division, motility, and biofilm formation. RcsB regulates transcription either as a homodimer or together with auxiliary regulators, such as RcsA, BglJ, and GadE in Escherichia coli. In this study, we show that RcsB in addition forms heterodimers with MatA (also known as EcpR) and with DctR. Our data suggest that the MatA-dependent transcription regulation is mediated by the MatA-RcsB heterodimer and is independent of RcsB phosphorylation. Furthermore, we analyzed the relevance of amino acid residues of the active quintet of conserved residues, and of surface-exposed residues for activity of RcsB. The data suggest that the activity of the phosphorylation-dependent dimers, such as RcsA-RcsB and RcsB-RcsB, is affected by mutation of residues in the vicinity of the phosphorylation site, suggesting that a phosphorylation-induced structural change modulates their activity. In contrast, the phosphorylation-independent heterodimers BglJ-RcsB and MatA-RcsB are affected by only very few mutations. Heterodimerization of RcsB with various auxiliary regulators and their differential dependence on phosphorylation add an additional level of control to the Rcs system that is operating at the output level.
Rcs磷酸化信号转导途径是一种由细胞包膜应激诱导的双组分信号转导系统。该信号系统的应答调节因子RcsB是一种多效转录调节因子，参与多种应激反应、细胞分裂、运动性和生物膜形成的调控。在大肠杆菌中，RcsB作为同型二聚体或与辅助调节因子（如RcsA、BglJ和GadE）一起调节转录。在本研究中，我们发现RcsB还能与MatA（也称为EcpR）和DctR形成异源二聚体。我们的数据表明，MatA依赖的转录调控是由MatA-RcsB异源二聚体介导的，且独立于RcsB的磷酸化。此外，我们分析了保守残基活性五联体的氨基酸残基以及表面暴露残基对RcsB活性的相关性。数据表明，磷酸化依赖的二聚体（如RcsA-RcsB和RcsB-RcsB）的活性受磷酸化位点附近残基突变的影响，这表明磷酸化诱导的结构变化调节了它们的活性。相反，磷酸化非依赖的异源二聚体BglJ-RcsB和MatA-RcsB仅受极少数突变的影响。RcsB与各种辅助调节因子的异源二聚化及其对磷酸化的不同依赖性为在输出水平起作用的Rcs系统增加了额外的控制层次。
