%0 Journal Article %T Peptidoglycan Crosslinking Relaxation Plays an Important Role in Staphylococcus aureus WalKR-Dependent Cell Viability %+ Biologie des Bactéries Pathogènes à Gram-positif %+ Microscopie ultrastructurale (plate-forme) %+ Chimie des biomolécules %A Delauné, Aurelia %A Poupel, Olivier %A Mallet, Adeline %A Coïc, Yves-Marie %A Msadek, Tarek %A Dubrac, Sarah %Z This work was supported by research funds from the European Commission (StaphDynamics [LHSM-CT-2006-019064] and BaSysBio [LSHG-CT-2006-037469] grants), the Centre National de la Recherche Scientifique (CNRS URA 2172), Agence Nationale de la Recherche (ANR GrabIron and NaBab) and the Institut Pasteur (PTR N°256 and PTR N°336). Aurelia Delaune received a Young Scientist Fellowship from the Conseil Pasteur-Weizmann. %< avec comité de lecture %@ 1932-6203 %J PLoS ONE %I Public Library of Science %V 6 %N 2 %P e17054 %8 2011-02-28 %D 2011 %R 10.1371/journal.pone.0017054 %M 21386961 %Z Life Sciences [q-bio]/Microbiology and ParasitologyJournal articles %X The WalKR two-component system is essential for viability of Staphylococcus aureus, a major pathogen. We have shown that WalKR acts as the master controller of peptidoglycan metabolism, yet none of the identified regulon genes explain its requirement for cell viability. Transmission electron micrographs revealed cell wall thickening and aberrant division septa in the absence of WalKR, suggesting its requirement may be linked to its role in coordinating cell wall metabolism and cell division. We therefore tested whether uncoupling autolysin gene expression from WalKR-dependent regulation could compensate for its essential nature. Uncoupled expression of genes encoding lytic transglycosylases or amidases did not restore growth to a WalKR-depleted strain. We identified only two WalKR-regulon genes whose expression restored cell viability in the absence of WalKR: lytM and ssaA. Neither of these two genes are essential under our conditions and a ΔlytM ΔssaA mutant does not present any growth defect. LytM is a glycyl-glycyl endopeptidase, hydrolyzing the pentaglycine interpeptide crossbridge, and SsaA belongs to the CHAP amidase family, members of which such as LysK and LytA have been shown to have D-alanyl-glycyl endopeptidase activity, cleaving between the crossbridge and the stem peptide. Taken together, our results strongly suggest that peptidoglycan crosslinking relaxation through crossbridge hydrolysis plays a crucial role in the essential requirement of the WalKR system for cell viability. %G English %Z We would like to thank Fritz Götz for the kind gift of plasmid pCXlss7 and many helpful suggestions, as well as Marie-Christine Prévost (Institut Pasteur, Ultrastructural Microscopy Platform), Françoise Baleux (Institut Pasteur, Chemistry of Biomolecules), Ivo Gomperts-Boneca and Simon J. Foster for helpful discussion. %2 https://pasteur.hal.science/pasteur-02870016/document %2 https://pasteur.hal.science/pasteur-02870016/file/journal.pone.0017054.PDF %L pasteur-02870016 %U https://pasteur.hal.science/pasteur-02870016 %~ PASTEUR %~ CNRS %~ OPENAIRE %~ ANR