Serine/Threonine Protein Phosphatase-Mediated Control of the Peptidoglycan Cross-Linking <sc>l</sc>,<sc>d</sc><sc>-</sc>Transpeptidase Pathway in <named-content content-type="genus-species">Enterococcus faecium</named-content>

ABSTRACT The last step of peptidoglycan polymerization involves two families of unrelated transpeptidases that are the essential targets of β-lactam antibiotics. d,d-transpeptidases of the penicillin-binding protein (PBP) family are active-site serine enzymes that use pentapeptide precursors and are...

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Autores principales:	Emmanuelle Sacco, Mélanie Cortes, Nathalie Josseaume, Louis B. Rice, Jean-Luc Mainardi, Michel Arthur
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Lenguaje:	EN
Publicado:	American Society for Microbiology 2014
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/6859b98ddb5544f7ae118d19c4ba878a
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spelling	oai:doaj.org-article:6859b98ddb5544f7ae118d19c4ba878a2021-11-15T15:47:22ZSerine/Threonine Protein Phosphatase-Mediated Control of the Peptidoglycan Cross-Linking <sc>l</sc>,<sc>d</sc><sc>-</sc>Transpeptidase Pathway in <named-content content-type="genus-species">Enterococcus faecium</named-content>10.1128/mBio.01446-142150-7511https://doaj.org/article/6859b98ddb5544f7ae118d19c4ba878a2014-08-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.01446-14https://doaj.org/toc/2150-7511ABSTRACT The last step of peptidoglycan polymerization involves two families of unrelated transpeptidases that are the essential targets of β-lactam antibiotics. d,d-transpeptidases of the penicillin-binding protein (PBP) family are active-site serine enzymes that use pentapeptide precursors and are the main or exclusive cross-linking enzymes in nearly all bacteria. However, peptidoglycan cross-linking is performed mainly by active-site cysteine l,d-transpeptidases that use tetrapeptides in Mycobacterium tuberculosis, Clostridium difficile, and β-lactam-resistant mutants of Enterococcus faecium. We have investigated reprogramming of the E. faecium peptidoglycan assembly pathway by a switch from pentapeptide to tetrapeptide precursors and bypass of PBPs by l,d-transpeptidase Ldtfm. Mutational alterations of two signal transduction systems were necessary and sufficient for activation of the l,d-transpeptidation pathway, which is essentially cryptic in wild-type strains. The first one is a classical two-component regulatory system, DdcRS, that controls the activity of Ldtfm at the substrate level. As previously described, loss of DdcS phosphatase activity leads to production of the d,d-carboxypeptidase DdcY and conversion of the pentapeptide into the tetrapeptide substrate of Ldtfm. Here we show that full bypass of PBPs by Ldtfm also requires increased Ser/Thr protein phosphorylation resulting from impaired activity of phosphoprotein phosphatase StpA. This enzyme negatively controlled the level of protein phosphorylation both by direct dephosphorylation of target proteins and by dephosphorylation of its cognate kinase Stk. In combination with production of DdcY, increased protein phosphorylation by this eukaryotic-enzyme-like Ser/Thr protein kinase was sufficient for activation of the l,d-transpeptidation pathway in the absence of mutational alteration of peptidoglycan synthesis enzymes. IMPORTANCE The mechanism of acquisition of high-level ampicillin resistance involving bypass of the penicillin-binding proteins (PBPs) by l,d-transpeptidase Ldtfm was incompletely understood, as production of tetrapeptide precursors following transcriptional activation of the ddc locus by the DdcRS two-component regulatory system was necessary but not sufficient for full activation of the l,d-transpeptidation pathway. Here, we identified the release of a negative control of Ser/Thr protein phosphorylation mediated by phosphatase StpA as the additional factor essential for ampicillin resistance. Thus, bypass of PBPs by Ldtfm requires the modification of signal transduction regulatory systems without any gain of function by mutational alteration of peptidoglycan biosynthetic enzymes. In contrast, previously characterized mechanisms of antibiotic resistance involve horizontal gene transfer and mutational alteration of drug targets. Activation of the l,d-transpeptidation pathway reported in this study is an unprecedented mechanism of emergence of a new metabolic pathway since it involved the recruitment of preexisting functions following modifications of regulatory circuits.Emmanuelle SaccoMélanie CortesNathalie JosseaumeLouis B. RiceJean-Luc MainardiMichel ArthurAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 5, Iss 4 (2014)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Emmanuelle Sacco Mélanie Cortes Nathalie Josseaume Louis B. Rice Jean-Luc Mainardi Michel Arthur Serine/Threonine Protein Phosphatase-Mediated Control of the Peptidoglycan Cross-Linking <sc>l</sc>,<sc>d</sc><sc>-</sc>Transpeptidase Pathway in <named-content content-type="genus-species">Enterococcus faecium</named-content>
description	ABSTRACT The last step of peptidoglycan polymerization involves two families of unrelated transpeptidases that are the essential targets of β-lactam antibiotics. d,d-transpeptidases of the penicillin-binding protein (PBP) family are active-site serine enzymes that use pentapeptide precursors and are the main or exclusive cross-linking enzymes in nearly all bacteria. However, peptidoglycan cross-linking is performed mainly by active-site cysteine l,d-transpeptidases that use tetrapeptides in Mycobacterium tuberculosis, Clostridium difficile, and β-lactam-resistant mutants of Enterococcus faecium. We have investigated reprogramming of the E. faecium peptidoglycan assembly pathway by a switch from pentapeptide to tetrapeptide precursors and bypass of PBPs by l,d-transpeptidase Ldtfm. Mutational alterations of two signal transduction systems were necessary and sufficient for activation of the l,d-transpeptidation pathway, which is essentially cryptic in wild-type strains. The first one is a classical two-component regulatory system, DdcRS, that controls the activity of Ldtfm at the substrate level. As previously described, loss of DdcS phosphatase activity leads to production of the d,d-carboxypeptidase DdcY and conversion of the pentapeptide into the tetrapeptide substrate of Ldtfm. Here we show that full bypass of PBPs by Ldtfm also requires increased Ser/Thr protein phosphorylation resulting from impaired activity of phosphoprotein phosphatase StpA. This enzyme negatively controlled the level of protein phosphorylation both by direct dephosphorylation of target proteins and by dephosphorylation of its cognate kinase Stk. In combination with production of DdcY, increased protein phosphorylation by this eukaryotic-enzyme-like Ser/Thr protein kinase was sufficient for activation of the l,d-transpeptidation pathway in the absence of mutational alteration of peptidoglycan synthesis enzymes. IMPORTANCE The mechanism of acquisition of high-level ampicillin resistance involving bypass of the penicillin-binding proteins (PBPs) by l,d-transpeptidase Ldtfm was incompletely understood, as production of tetrapeptide precursors following transcriptional activation of the ddc locus by the DdcRS two-component regulatory system was necessary but not sufficient for full activation of the l,d-transpeptidation pathway. Here, we identified the release of a negative control of Ser/Thr protein phosphorylation mediated by phosphatase StpA as the additional factor essential for ampicillin resistance. Thus, bypass of PBPs by Ldtfm requires the modification of signal transduction regulatory systems without any gain of function by mutational alteration of peptidoglycan biosynthetic enzymes. In contrast, previously characterized mechanisms of antibiotic resistance involve horizontal gene transfer and mutational alteration of drug targets. Activation of the l,d-transpeptidation pathway reported in this study is an unprecedented mechanism of emergence of a new metabolic pathway since it involved the recruitment of preexisting functions following modifications of regulatory circuits.
format	article
author	Emmanuelle Sacco Mélanie Cortes Nathalie Josseaume Louis B. Rice Jean-Luc Mainardi Michel Arthur
author_facet	Emmanuelle Sacco Mélanie Cortes Nathalie Josseaume Louis B. Rice Jean-Luc Mainardi Michel Arthur
author_sort	Emmanuelle Sacco
title	Serine/Threonine Protein Phosphatase-Mediated Control of the Peptidoglycan Cross-Linking <sc>l</sc>,<sc>d</sc><sc>-</sc>Transpeptidase Pathway in <named-content content-type="genus-species">Enterococcus faecium</named-content>
title_short	Serine/Threonine Protein Phosphatase-Mediated Control of the Peptidoglycan Cross-Linking <sc>l</sc>,<sc>d</sc><sc>-</sc>Transpeptidase Pathway in <named-content content-type="genus-species">Enterococcus faecium</named-content>
title_full	Serine/Threonine Protein Phosphatase-Mediated Control of the Peptidoglycan Cross-Linking <sc>l</sc>,<sc>d</sc><sc>-</sc>Transpeptidase Pathway in <named-content content-type="genus-species">Enterococcus faecium</named-content>
title_fullStr	Serine/Threonine Protein Phosphatase-Mediated Control of the Peptidoglycan Cross-Linking <sc>l</sc>,<sc>d</sc><sc>-</sc>Transpeptidase Pathway in <named-content content-type="genus-species">Enterococcus faecium</named-content>
title_full_unstemmed	Serine/Threonine Protein Phosphatase-Mediated Control of the Peptidoglycan Cross-Linking <sc>l</sc>,<sc>d</sc><sc>-</sc>Transpeptidase Pathway in <named-content content-type="genus-species">Enterococcus faecium</named-content>
title_sort	serine/threonine protein phosphatase-mediated control of the peptidoglycan cross-linking <sc>l</sc>,<sc>d</sc><sc>-</sc>transpeptidase pathway in <named-content content-type="genus-species">enterococcus faecium</named-content>
publisher	American Society for Microbiology
publishDate	2014
url	https://doaj.org/article/6859b98ddb5544f7ae118d19c4ba878a
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Serine/Threonine Protein Phosphatase-Mediated Control of the Peptidoglycan Cross-Linking <sc>l</sc>,<sc>d</sc><sc>-</sc>Transpeptidase Pathway in <named-content content-type="genus-species">Enterococcus faecium</named-content>

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