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Small RNA ‐binding protein RapZ mediates cell envelope precursor sensing and signaling in Escherichia coli
Author(s) -
Khan Muna A,
DuricaMitic Svetlana,
Göpel Yvonne,
Heermann Ralf,
Görke Boris
Publication year - 2020
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2019103848
Subject(s) - biology , escherichia coli , rna binding protein , rna , envelope (radar) , microbiology and biotechnology , biochemistry , gene , telecommunications , radar , computer science
The RNA ‐binding protein RapZ cooperates with small RNA s ( sRNA s) 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.