Anti-adaptors provide multiple modes for regulation of the RssB adaptor protein
Anti-adaptors provide multiple modes for regulation of the RssB adaptor protein
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DOI：
10.1101/gad.229617.113
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发表时间：
2013-12-15
影响因子：
10.5
通讯作者：
Gottesman, Susan
中科院分区：
文献类型：
--
作者：
Battesti, Aurelia;Hoskins, Joel R.;Gottesman, Susan
RpoS是一种RNA聚合酶sigma因子，控制着大肠杆菌及相关细菌对多种应激反应的反应。在非胁迫条件下，RpoS会被ClpXP快速降解，ClpXP是由响应调节蛋白家族成员之一的接头蛋白RssB介导的。作为对压力的反应，rpo的退化停止。在不同的应激条件下产生的小的抗接头蛋白- irap， IraM和IraD -阻断了RpoS的降解。分离出抗IraP或IraM的RssB突变体，并在体内和体外进行分析。每个抗接头在与RssB的相互作用和对RssB突变体的敏感性方面都是独一无二的。一类突变体定义了一个靠近磷酸化位点的RssB n端区域，该区域对与IraP相互作用至关重要，但对IraM和IraD功能没有必要。第二类，在RssB c端pp2c样结构域，导致RssB功能的激活。这些突变体允许反应调节因子在没有磷酸化的情况下发挥作用，但不消除与抗接头的相互作用。这类突变体对抗接头具有广泛的抗性，并且与在一种非常不同的PP2C蛋白中发现的组成型激活突变体相似。突变体提供了洞察抗适配器如何干扰RssB反应调节功能和激活。
RpoS, an RNA polymerase sigma factor, controls the response of Escherichia coli and related bacteria to multiple stress responses. During nonstress conditions, RpoS is rapidly degraded by ClpXP, mediated by the adaptor protein RssB, a member of the response regulator family. In response to stress, RpoS degradation ceases. Small anti-adaptor proteins-IraP, IraM, and IraD, each made under a different stress condition-block RpoS degradation. RssB mutants resistant to either IraP or IraM were isolated and analyzed in vivo and in vitro. Each of the anti-adaptors is unique in its interaction with RssB and sensitivity to RssB mutants. One class of mutants defined an RssB N-terminal region close to the phosphorylation site and critical for interaction with IraP but unnecessary for IraM and IraD function. A second class, in the RssB C-terminal PP2C-like domain, led to activation of RssB function. These mutants allowed the response regulator to act in the absence of phosphorylation but did not abolish interaction with anti-adaptors. This class of mutants is broadly resistant to the anti-adaptors and bears similarity to constitutively activated mutants found in a very different PP2C protein. The mutants provide insight into how the anti-adaptors perturb RssB response regulator function and activation.