structural sudies of ClpS, dem RpoS/RssB-Target System und FtsH

细菌细胞中蛋白质的合成和降解受到许多分子伴侣和蛋白水解酶的严格控制。尤其重要的是ClpAP和ClpXP蛋白酶复合体，它们是错误折叠的胞浆和短寿命多肽的特异性靶标，而FtsH蛋白酶主要作用于完整的膜蛋白。ClpAP和ClpXP是由属于ATPase AAA家族的ClpP蛋白水解亚单位和ClpA或ClpX伴侣组成的依赖于ATP的过程性蛋白水解酶，而FtsH将这两种功能结合在一个多肽链中。有一些已知的蛋白质可以作为ClpXP和ClpAP的底物感受器。例如，底物感觉蛋白CLPS增强了ClpAP蛋白酶的底物特异性，而反应调节因子RSSB则专门针对编码了rpos的SS因子，以实现ClpXP介导的降解。

Protein synthesis and degradation in the bacterial cell is tightly controlled by a number of molecular chaperones and proteases. Particularly important are the ClpAP and ClpXP protease complexes, which are specific targets of misfolded cytosolic and short-lived polypeptides, whereas the FtsH protease acts primarily on integral membrane proteins. ClpAP and ClpXP are ATP-dependent, processive proteases composed of a ClpP proteolytic subunit and either a ClpA or ClpX chaperone belonging to the AAA family of ATPases while FtsH combines both functions within one polypeptide chain. There are a few proteins known which play a role as substrate sensors for ClpXP and ClpAP. The substrate sensory protein ClpS for instance enhances the substrate specificity of the ClpAP protease and the response regulator RssB specifically targets the rpos-encoded sS factor for ClpXP-mediated degradation.