Identification of Two Regulators of Virulence That Are Conserved in <italic toggle="yes">Klebsiella pneumoniae</italic> Classical and Hypervirulent Strains

ABSTRACT Klebsiella pneumoniae is widely recognized as a pathogen with a propensity for acquiring antibiotic resistance. It is capable of causing a range of hospital-acquired infections (urinary tract infections [UTI], pneumonia, sepsis) and community-acquired invasive infections. The genetic hetero...

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Autores principales:	Michelle Palacios, Taryn A. Miner, Daniel R. Frederick, Victoria E. Sepulveda, Joshua D. Quinn, Kimberly A. Walker, Virginia L. Miller
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2018
Materias:	EmrR KvrA KvrB MarR ST258 SlyA Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/f39045d829a44c37afed7e39105cd7c3
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spelling	oai:doaj.org-article:f39045d829a44c37afed7e39105cd7c32021-11-15T16:00:14ZIdentification of Two Regulators of Virulence That Are Conserved in <italic toggle="yes">Klebsiella pneumoniae</italic> Classical and Hypervirulent Strains10.1128/mBio.01443-182150-7511https://doaj.org/article/f39045d829a44c37afed7e39105cd7c32018-09-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.01443-18https://doaj.org/toc/2150-7511ABSTRACT Klebsiella pneumoniae is widely recognized as a pathogen with a propensity for acquiring antibiotic resistance. It is capable of causing a range of hospital-acquired infections (urinary tract infections [UTI], pneumonia, sepsis) and community-acquired invasive infections. The genetic heterogeneity of K. pneumoniae isolates complicates our ability to understand the virulence of K. pneumoniae. Characterization of virulence factors conserved between strains as well as strain-specific factors will improve our understanding of this important pathogen. The MarR family of regulatory proteins is widely distributed in bacteria and regulates cellular processes such as antibiotic resistance and the expression of virulence factors. Klebsiella encodes numerous MarR-like proteins, and they likely contribute to the ability of K. pneumoniae to respond to and survive under a wide variety of environmental conditions, including those present in the human body. We tested loss-of-function mutations in all the marR homologues in a murine pneumonia model and found that two (kvrA and kvrB) significantly impacted the virulence of K1 and K2 capsule type hypervirulent (hv) strains and that kvrA affected the virulence of a sequence type 258 (ST258) classical strain. In the hv strains, kvrA and kvrB mutants displayed phenotypes associated with reduced capsule production, mucoviscosity, and transcription from galF and manC promoters that drive expression of capsule synthesis genes. In contrast, kvrA and kvrB mutants in the ST258 strain had no effect on capsule gene expression or capsule-related phenotypes. Thus, KvrA and KvrB affect virulence in classical and hv strains but the effect on virulence may not be exclusively due to effects on capsule production. IMPORTANCE In addition to having a reputation as the causative agent for hospital-acquired infections as well as community-acquired invasive infections, Klebsiella pneumoniae has gained widespread attention as a pathogen with a propensity for acquiring antibiotic resistance. Due to the rapid emergence of carbapenem resistance among K. pneumoniae strains, a better understanding of virulence mechanisms and identification of new potential drug targets are needed. This study identified two novel regulators (KvrA and KvrB) of virulence in K. pneumoniae and demonstrated that their effect on virulence in invasive strains is likely due in part to effects on capsule production (a major virulence determinant) and hypermucoviscosity. KvrA also impacts the virulence of classical strains but does not appear to affect capsule gene expression in this strain. KvrA and KvrB are conserved among K. pneumoniae strains and thus could regulate capsule expression and virulence in diverse strains regardless of capsule type.Michelle PalaciosTaryn A. MinerDaniel R. FrederickVictoria E. SepulvedaJoshua D. QuinnKimberly A. WalkerVirginia L. MillerAmerican Society for MicrobiologyarticleEmrRKvrAKvrBMarRST258SlyAMicrobiologyQR1-502ENmBio, Vol 9, Iss 4 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	EmrR KvrA KvrB MarR ST258 SlyA Microbiology QR1-502
spellingShingle	EmrR KvrA KvrB MarR ST258 SlyA Microbiology QR1-502 Michelle Palacios Taryn A. Miner Daniel R. Frederick Victoria E. Sepulveda Joshua D. Quinn Kimberly A. Walker Virginia L. Miller Identification of Two Regulators of Virulence That Are Conserved in <italic toggle="yes">Klebsiella pneumoniae</italic> Classical and Hypervirulent Strains
description	ABSTRACT Klebsiella pneumoniae is widely recognized as a pathogen with a propensity for acquiring antibiotic resistance. It is capable of causing a range of hospital-acquired infections (urinary tract infections [UTI], pneumonia, sepsis) and community-acquired invasive infections. The genetic heterogeneity of K. pneumoniae isolates complicates our ability to understand the virulence of K. pneumoniae. Characterization of virulence factors conserved between strains as well as strain-specific factors will improve our understanding of this important pathogen. The MarR family of regulatory proteins is widely distributed in bacteria and regulates cellular processes such as antibiotic resistance and the expression of virulence factors. Klebsiella encodes numerous MarR-like proteins, and they likely contribute to the ability of K. pneumoniae to respond to and survive under a wide variety of environmental conditions, including those present in the human body. We tested loss-of-function mutations in all the marR homologues in a murine pneumonia model and found that two (kvrA and kvrB) significantly impacted the virulence of K1 and K2 capsule type hypervirulent (hv) strains and that kvrA affected the virulence of a sequence type 258 (ST258) classical strain. In the hv strains, kvrA and kvrB mutants displayed phenotypes associated with reduced capsule production, mucoviscosity, and transcription from galF and manC promoters that drive expression of capsule synthesis genes. In contrast, kvrA and kvrB mutants in the ST258 strain had no effect on capsule gene expression or capsule-related phenotypes. Thus, KvrA and KvrB affect virulence in classical and hv strains but the effect on virulence may not be exclusively due to effects on capsule production. IMPORTANCE In addition to having a reputation as the causative agent for hospital-acquired infections as well as community-acquired invasive infections, Klebsiella pneumoniae has gained widespread attention as a pathogen with a propensity for acquiring antibiotic resistance. Due to the rapid emergence of carbapenem resistance among K. pneumoniae strains, a better understanding of virulence mechanisms and identification of new potential drug targets are needed. This study identified two novel regulators (KvrA and KvrB) of virulence in K. pneumoniae and demonstrated that their effect on virulence in invasive strains is likely due in part to effects on capsule production (a major virulence determinant) and hypermucoviscosity. KvrA also impacts the virulence of classical strains but does not appear to affect capsule gene expression in this strain. KvrA and KvrB are conserved among K. pneumoniae strains and thus could regulate capsule expression and virulence in diverse strains regardless of capsule type.
format	article
author	Michelle Palacios Taryn A. Miner Daniel R. Frederick Victoria E. Sepulveda Joshua D. Quinn Kimberly A. Walker Virginia L. Miller
author_facet	Michelle Palacios Taryn A. Miner Daniel R. Frederick Victoria E. Sepulveda Joshua D. Quinn Kimberly A. Walker Virginia L. Miller
author_sort	Michelle Palacios
title	Identification of Two Regulators of Virulence That Are Conserved in <italic toggle="yes">Klebsiella pneumoniae</italic> Classical and Hypervirulent Strains
title_short	Identification of Two Regulators of Virulence That Are Conserved in <italic toggle="yes">Klebsiella pneumoniae</italic> Classical and Hypervirulent Strains
title_full	Identification of Two Regulators of Virulence That Are Conserved in <italic toggle="yes">Klebsiella pneumoniae</italic> Classical and Hypervirulent Strains
title_fullStr	Identification of Two Regulators of Virulence That Are Conserved in <italic toggle="yes">Klebsiella pneumoniae</italic> Classical and Hypervirulent Strains
title_full_unstemmed	Identification of Two Regulators of Virulence That Are Conserved in <italic toggle="yes">Klebsiella pneumoniae</italic> Classical and Hypervirulent Strains
title_sort	identification of two regulators of virulence that are conserved in <italic toggle="yes">klebsiella pneumoniae</italic> classical and hypervirulent strains
publisher	American Society for Microbiology
publishDate	2018
url	https://doaj.org/article/f39045d829a44c37afed7e39105cd7c3
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Identification of Two Regulators of Virulence That Are Conserved in <italic toggle="yes">Klebsiella pneumoniae</italic> Classical and Hypervirulent Strains

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