The RNA-binding protein RapZ cooperates with small RNAs (sRNAs) GlmY and GlmZ to regulate the glmS mRNA in Escherichia coli. Enzyme GlmS synthesizes glucosamine-6-phosphate (GlcN6P), initiating cell envelope biosynthesis. GlmZ activates glmS expression by base-pairing. When GlcN6P is ample, GlmZ is bound by RapZ and degraded through ribonuclease recruitment. Upon GlcN6P depletion, the decoy sRNA GlmY accumulates through a previously unknown mechanism and sequesters RapZ, suppressing GlmZ decay. This circuit ensures GlcN6P homeostasis and thereby envelope integrity. In this work, we identify RapZ as GlcN6P receptor. GlcN6P-free RapZ stimulates phosphorylation of the two-component system QseE/QseF by interaction, which in turn activates glmY expression. Elevated GlmY levels sequester RapZ into stable complexes, which prevents GlmZ decay, promoting glmS expression. Binding of GlmY also prevents RapZ from activating QseE/QseF, generating a negative feedback loop limiting the response. When GlcN6P is replenished, GlmY is released from RapZ and rapidly degraded. We reveal a multifunctional sRNA-binding protein that dynamically engages into higher-order complexes for metabolite signaling.

中文翻译：

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小RNA结合蛋白RapZ在大肠杆菌中介导细胞包膜前体的传感和信号传导。

RNA结合蛋白RapZ与小RNA（sRNA）GlmY和GlmZ协同调节大肠杆菌中的glmS mRNA。酶GlmS合成6-磷酸氨基葡萄糖（GlcN6P），启动细胞包膜的生物合成。GlmZ通过碱基配对激活glmS表达。当GlcN6P足够时，GlmZ被RapZ结合并通过核糖核酸酶募集而降解。GlcN6P耗尽后，诱饵sRNA GlmY会通过以前未知的机制积累并隔离RapZ，从而抑制GlmZ衰变。该电路可确保GlcN6P的动态平衡，从而确保包封的完整性。在这项工作中，我们确定RapZ为GlcN6P受体。不含GlcN6P的RapZ通过相互作用刺激两组分系统QseE / QseF的磷酸化，进而激活glmY表达。升高的GlmY水平将RapZ螯合为稳定的复合物，从而阻止了GlmZ的衰变，促进glmS表达。绑定GlmY还可以阻止RapZ激活QseE / QseF，从而生成限制响应的负反馈循环。补充GlcN6P时，GlmY从RapZ中释放出来并迅速降解。我们揭示了一种多功能的sRNA结合蛋白，可以动态地参与高阶复合物的代谢物信号传导。