Reciprocal Regulation of Cephalosporin Resistance in <named-content content-type="genus-species">Enterococcus faecalis</named-content>

ABSTRACT Antibiotic-resistant enterococci are major causes of hospital-acquired infections and therefore represent a serious public health problem. One well-known risk factor for the acquisition of hospital-acquired enterococcal infections is prior therapy with broad-spectrum cephalosporin antibioti...

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Autores principales:	Christopher J. Kristich, Jaime L. Little, Cherisse L. Hall, Jessica S. Hoff
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2011
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/a810828359b54543abfa151e9b2c0dd8
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spelling	oai:doaj.org-article:a810828359b54543abfa151e9b2c0dd82021-11-15T15:38:48ZReciprocal Regulation of Cephalosporin Resistance in <named-content content-type="genus-species">Enterococcus faecalis</named-content>10.1128/mBio.00199-112150-7511https://doaj.org/article/a810828359b54543abfa151e9b2c0dd82011-12-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00199-11https://doaj.org/toc/2150-7511ABSTRACT Antibiotic-resistant enterococci are major causes of hospital-acquired infections and therefore represent a serious public health problem. One well-known risk factor for the acquisition of hospital-acquired enterococcal infections is prior therapy with broad-spectrum cephalosporin antibiotics. Enterococci can proliferate in patients undergoing cephalosporin therapy due to intrinsic cephalosporin resistance, a characteristic of the genus Enterococcus. However, the molecular basis for cephalosporin resistance in E. faecalis has yet to be adequately elucidated. Previously we determined that a putative Ser/Thr kinase, IreK (formerly PrkC), is required for intrinsic cephalosporin resistance in E. faecalis. Here we show that kinase activity is required for cephalosporin resistance and, further, that resistance in E. faecalis is reciprocally regulated by IreK and IreP, a PP2C-type protein phosphatase encoded immediately upstream of IreK. Mutants of two divergent lineages of E. faecalis lacking IreP exhibit remarkable hyperresistance to cephalosporins but not to antibiotics targeting other cellular processes. Further genetic analyses indicate that hyperresistance of the IreP mutant is mediated by the IreK kinase. Additionally, competition experiments reveal that hyperresistant ΔireP mutants exhibit a substantial fitness defect in the absence of antibiotics, providing an evolutionary rationale for the use of a complex signaling system to control intrinsic cephalosporin resistance. These results support a model in which IreK and IreP act antagonistically via protein phosphorylation and dephosphorylation as part of a signal transduction circuit to regulate cellular adaptation to cephalosporin-induced stress. IMPORTANCE As a major cause of hospital-acquired infections, antibiotic-resistant enterococci represent a serious public health problem. Enterococci are well-known to exhibit intrinsic resistance to broad-spectrum cephalosporin antibiotics, a trait that enables them to proliferate in patients undergoing cephalosporin therapy, thereby predisposing these patients to acquisition of an enterococcal infection. Thus, inhibition of enterococcal cephalosporin resistance could represent an effective new strategy to prevent the emergence of hospital-acquired enterococcal infections. At this time, however, the molecular basis for cephalosporin resistance in E. faecalis is poorly understood. Our results begin to unravel the details of a new phosphorylation-dependent signal transduction system that controls cephalosporin resistance in enterococci. Deeper understanding of the mechanism underlying cephalosporin resistance in E. faecalis may enable the development of new therapeutics designed to reduce the incidence of hospital-acquired enterococcal infections.Christopher J. KristichJaime L. LittleCherisse L. HallJessica S. HoffAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 2, Iss 6 (2011)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Christopher J. Kristich Jaime L. Little Cherisse L. Hall Jessica S. Hoff Reciprocal Regulation of Cephalosporin Resistance in <named-content content-type="genus-species">Enterococcus faecalis</named-content>
description	ABSTRACT Antibiotic-resistant enterococci are major causes of hospital-acquired infections and therefore represent a serious public health problem. One well-known risk factor for the acquisition of hospital-acquired enterococcal infections is prior therapy with broad-spectrum cephalosporin antibiotics. Enterococci can proliferate in patients undergoing cephalosporin therapy due to intrinsic cephalosporin resistance, a characteristic of the genus Enterococcus. However, the molecular basis for cephalosporin resistance in E. faecalis has yet to be adequately elucidated. Previously we determined that a putative Ser/Thr kinase, IreK (formerly PrkC), is required for intrinsic cephalosporin resistance in E. faecalis. Here we show that kinase activity is required for cephalosporin resistance and, further, that resistance in E. faecalis is reciprocally regulated by IreK and IreP, a PP2C-type protein phosphatase encoded immediately upstream of IreK. Mutants of two divergent lineages of E. faecalis lacking IreP exhibit remarkable hyperresistance to cephalosporins but not to antibiotics targeting other cellular processes. Further genetic analyses indicate that hyperresistance of the IreP mutant is mediated by the IreK kinase. Additionally, competition experiments reveal that hyperresistant ΔireP mutants exhibit a substantial fitness defect in the absence of antibiotics, providing an evolutionary rationale for the use of a complex signaling system to control intrinsic cephalosporin resistance. These results support a model in which IreK and IreP act antagonistically via protein phosphorylation and dephosphorylation as part of a signal transduction circuit to regulate cellular adaptation to cephalosporin-induced stress. IMPORTANCE As a major cause of hospital-acquired infections, antibiotic-resistant enterococci represent a serious public health problem. Enterococci are well-known to exhibit intrinsic resistance to broad-spectrum cephalosporin antibiotics, a trait that enables them to proliferate in patients undergoing cephalosporin therapy, thereby predisposing these patients to acquisition of an enterococcal infection. Thus, inhibition of enterococcal cephalosporin resistance could represent an effective new strategy to prevent the emergence of hospital-acquired enterococcal infections. At this time, however, the molecular basis for cephalosporin resistance in E. faecalis is poorly understood. Our results begin to unravel the details of a new phosphorylation-dependent signal transduction system that controls cephalosporin resistance in enterococci. Deeper understanding of the mechanism underlying cephalosporin resistance in E. faecalis may enable the development of new therapeutics designed to reduce the incidence of hospital-acquired enterococcal infections.
format	article
author	Christopher J. Kristich Jaime L. Little Cherisse L. Hall Jessica S. Hoff
author_facet	Christopher J. Kristich Jaime L. Little Cherisse L. Hall Jessica S. Hoff
author_sort	Christopher J. Kristich
title	Reciprocal Regulation of Cephalosporin Resistance in <named-content content-type="genus-species">Enterococcus faecalis</named-content>
title_short	Reciprocal Regulation of Cephalosporin Resistance in <named-content content-type="genus-species">Enterococcus faecalis</named-content>
title_full	Reciprocal Regulation of Cephalosporin Resistance in <named-content content-type="genus-species">Enterococcus faecalis</named-content>
title_fullStr	Reciprocal Regulation of Cephalosporin Resistance in <named-content content-type="genus-species">Enterococcus faecalis</named-content>
title_full_unstemmed	Reciprocal Regulation of Cephalosporin Resistance in <named-content content-type="genus-species">Enterococcus faecalis</named-content>
title_sort	reciprocal regulation of cephalosporin resistance in <named-content content-type="genus-species">enterococcus faecalis</named-content>
publisher	American Society for Microbiology
publishDate	2011
url	https://doaj.org/article/a810828359b54543abfa151e9b2c0dd8
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Reciprocal Regulation of Cephalosporin Resistance in <named-content content-type="genus-species">Enterococcus faecalis</named-content>

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