FliW antagonizes CsrA RNA binding by a noncompetitive allosteric mechanism
FliW antagonizes CsrA RNA binding by a noncompetitive allosteric mechanism
复制标题
DOI：
10.1073/pnas.1602455113
复制
发表时间：
2016-08-30
影响因子：
11.1
通讯作者：
Kearns, Daniel B.
中科院分区：
文献类型：
--
作者：
Mukherjee, Sampriti;Oshiro, Reid T.;Kearns, Daniel B.
CsrA（碳储存调节剂 A）是一种广泛分布的细菌 RNA 结合蛋白，可调节目标转录物的翻译起始和 mRNA 稳定性。在γ-变形菌中，CsrA 活性被一个或多个含有多个 CsrA 结合位点的小 RNA (sRNA) 竞争性拮抗，但在 γ-变形菌之外的细菌中，CsrA 被一种称为 FliW 的蛋白质拮抗。在这里，我们表明枯草芽孢杆菌的 FliW 不与 RNA 结合所需的 CsrA 残基结合。相反，对 FliW 拮抗作用 (crw) 具有抗性的 CsrA 突变体改变了先前未归因功能的变构表面上的 CsrA 残基。一些 crw 突变体废除了 CsrA-FliW 结合，但其他突变体则没有，这表明 FliW 和 RNA 相互作用并不相互排斥。我们得出结论，FliW 通过非竞争性机制抑制 CsrA，该机制与成熟的 sRNA 抑制剂显着不同。 FliWi 在细菌中与 CsrA 高度保守，似乎是 CsrA 调节的祖先形式，代表了 CsrA 控制的广泛非竞争性机制。
CsrA (carbon storage regulator A) is a widely distributed bacterial RNA binding protein that regulates translation initiation and mRNA stability of target transcripts. In gamma-proteobacteria, CsrA activity is competitively antagonized by one or more small RNAs (sRNAs) containing multiple CsrA binding sites, but CsrA in bacteria outside the gamma-proteobacteria is antagonized by a protein called FliW. Here we show that FliW of Bacillus subtilis does not bind to the same residues of CsrA required for RNA binding. Instead, CsrA mutants resistant to FliW antagonism (crw) altered residues of CsrA on an allosteric surface of previously unattributed function. Some crw mutants abolished CsrA-FliW binding, but others did not, suggesting that FliW and RNA interaction is not mutually exclusive. We conclude that FliW inhibits CsrA by a noncompetitive mechanism that differs dramatically from the well-established sRNA inhibitors. FliWis highly conserved with CsrA in bacteria, appears to be the ancestral form of CsrA regulation, and represents a widespread noncompetitive mechanism of CsrA control.