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MurAA, catalysing the first committed step in peptidoglycan biosynthesis, is a target of Clp‐dependent proteolysis in Bacillus subtilis
Author(s) -
Kock Holger,
Gerth Ulf,
Hecker Michael
Publication year - 2004
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2003.03875.x
Subject(s) - bacillus subtilis , biology , proteolysis , peptidoglycan , biosynthesis , biochemistry , microbiology and biotechnology , bacteria , cell wall , enzyme , genetics
Summary The carboxyvinyl transfer from phosphoenolpyruvate to UDP‐ N ‐acetylglucosamine is the first committed step in the pathway of peptidoglycan formation. This crucial reaction for bacterial cell growth is catalysed by the MurA enzymes. Gram‐negative bacteria carry one murA gene, whereas in a subgroup of Gram‐positive bacteria two separate paralogues, MurAA and MurAB, exist. This study provides evidence that in the Gram‐positive bacterium Bacillus subtilis , the MurAA protein is specifically degraded by the ClpCP protease. This Clp‐dependent degradation is especially enhanced upon entry into stationary phase, thus ensuring an immediate growth arrest due to stalled murein biosynthesis. The MurAA protein can therefore be addressed as a target of Clp‐dependent regulatory proteolysis such as the transcriptional regulators CtsR, ComK, Spx in B. subtilis , CtrA in Caulobacter crescentus or RpoS in Escherichia coli . Taking into account all other known regulatory targets of ATP‐dependent proteases, MurAA of B. subtilis represents the first example of a metabolic enzyme which is a unique regulatory substrate of Clp‐dependent proteolysis. Its function as a regulatory metabolic checkpoint resembles that of homoserine trans ‐succinylase (MetA) in E. coli which is similarly ATP‐dependently degraded.