<italic toggle="yes">csrR</italic>, a Paralog and Direct Target of CsrA, Promotes <named-content content-type="genus-species">Legionella pneumophila</named-content> Resilience in Water

ABSTRACT Critical to microbial versatility is the capacity to express the cohort of genes that increase fitness in different environments. Legionella pneumophila occupies extensive ecological space that includes diverse protists, pond water, engineered water systems, and mammalian lung macrophages....

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Autores principales:	Zachary D. Abbott, Helen Yakhnin, Paul Babitzke, Michele S. Swanson
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2015
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/068d6c9c8cc443ae84333ee56d704238
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spelling	oai:doaj.org-article:068d6c9c8cc443ae84333ee56d7042382021-11-15T15:49:03Z<italic toggle="yes">csrR</italic>, a Paralog and Direct Target of CsrA, Promotes <named-content content-type="genus-species">Legionella pneumophila</named-content> Resilience in Water10.1128/mBio.00595-152150-7511https://doaj.org/article/068d6c9c8cc443ae84333ee56d7042382015-07-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00595-15https://doaj.org/toc/2150-7511ABSTRACT Critical to microbial versatility is the capacity to express the cohort of genes that increase fitness in different environments. Legionella pneumophila occupies extensive ecological space that includes diverse protists, pond water, engineered water systems, and mammalian lung macrophages. One mechanism that equips this opportunistic pathogen to adapt to fluctuating conditions is a switch between replicative and transmissive cell types that is controlled by the broadly conserved regulatory protein CsrA. A striking feature of the legionellae surveyed is that each of 14 strains encodes 4 to 7 csrA-like genes, candidate regulators of distinct fitness traits. Here we focus on the one csrA paralog (lpg1593) that, like the canonical csrA, is conserved in all 14 strains surveyed. Phenotypic analysis revealed that long-term survival in tap water is promoted by the lpg1593 locus, which we name csrR (for “CsrA-similar protein for resilience”). As predicted by its GGA motif, csrR mRNA was bound directly by the canonical CsrA protein, as judged by electromobility shift and RNA-footprinting assays. Furthermore, CsrA repressed translation of csrR mRNA in vivo, as determined by analysis of csrR-gfp reporters, csrR mRNA stability in the presence and absence of csrA expression, and mutation of the CsrA binding site identified on the csrR mRNA. Thus, CsrA not only governs the transition from replication to transmission but also represses translation of its paralog csrR when nutrients are available. We propose that, during prolonged starvation, relief of CsrA repression permits CsrR protein to coordinate L. pneumophila's switch to a cell type that is resilient in water supplies. IMPORTANCE Persistence of L. pneumophila in water systems is a public health risk, and yet there is little understanding of the genetic determinants that equip this opportunistic pathogen to adapt to and survive in natural or engineered water systems. A potent regulator of this pathogen's intracellular life cycle is CsrA, a protein widely distributed among bacterial species that is understood quite well. Our finding that every sequenced L. pneumophila strain carries several csrA paralogs—including two common to all isolates—indicates that the legionellae exploit CsrA regulatory switches for multiple purposes. Our discovery that one paralog, CsrR, is a target of CsrA that enhances survival in water is an important step toward understanding colonization of the engineered environment by pathogenic L. pneumophila.Zachary D. AbbottHelen YakhninPaul BabitzkeMichele S. SwansonAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 6, Iss 3 (2015)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Zachary D. Abbott Helen Yakhnin Paul Babitzke Michele S. Swanson <italic toggle="yes">csrR</italic>, a Paralog and Direct Target of CsrA, Promotes <named-content content-type="genus-species">Legionella pneumophila</named-content> Resilience in Water
description	ABSTRACT Critical to microbial versatility is the capacity to express the cohort of genes that increase fitness in different environments. Legionella pneumophila occupies extensive ecological space that includes diverse protists, pond water, engineered water systems, and mammalian lung macrophages. One mechanism that equips this opportunistic pathogen to adapt to fluctuating conditions is a switch between replicative and transmissive cell types that is controlled by the broadly conserved regulatory protein CsrA. A striking feature of the legionellae surveyed is that each of 14 strains encodes 4 to 7 csrA-like genes, candidate regulators of distinct fitness traits. Here we focus on the one csrA paralog (lpg1593) that, like the canonical csrA, is conserved in all 14 strains surveyed. Phenotypic analysis revealed that long-term survival in tap water is promoted by the lpg1593 locus, which we name csrR (for “CsrA-similar protein for resilience”). As predicted by its GGA motif, csrR mRNA was bound directly by the canonical CsrA protein, as judged by electromobility shift and RNA-footprinting assays. Furthermore, CsrA repressed translation of csrR mRNA in vivo, as determined by analysis of csrR-gfp reporters, csrR mRNA stability in the presence and absence of csrA expression, and mutation of the CsrA binding site identified on the csrR mRNA. Thus, CsrA not only governs the transition from replication to transmission but also represses translation of its paralog csrR when nutrients are available. We propose that, during prolonged starvation, relief of CsrA repression permits CsrR protein to coordinate L. pneumophila's switch to a cell type that is resilient in water supplies. IMPORTANCE Persistence of L. pneumophila in water systems is a public health risk, and yet there is little understanding of the genetic determinants that equip this opportunistic pathogen to adapt to and survive in natural or engineered water systems. A potent regulator of this pathogen's intracellular life cycle is CsrA, a protein widely distributed among bacterial species that is understood quite well. Our finding that every sequenced L. pneumophila strain carries several csrA paralogs—including two common to all isolates—indicates that the legionellae exploit CsrA regulatory switches for multiple purposes. Our discovery that one paralog, CsrR, is a target of CsrA that enhances survival in water is an important step toward understanding colonization of the engineered environment by pathogenic L. pneumophila.
format	article
author	Zachary D. Abbott Helen Yakhnin Paul Babitzke Michele S. Swanson
author_facet	Zachary D. Abbott Helen Yakhnin Paul Babitzke Michele S. Swanson
author_sort	Zachary D. Abbott
title	<italic toggle="yes">csrR</italic>, a Paralog and Direct Target of CsrA, Promotes <named-content content-type="genus-species">Legionella pneumophila</named-content> Resilience in Water
title_short	<italic toggle="yes">csrR</italic>, a Paralog and Direct Target of CsrA, Promotes <named-content content-type="genus-species">Legionella pneumophila</named-content> Resilience in Water
title_full	<italic toggle="yes">csrR</italic>, a Paralog and Direct Target of CsrA, Promotes <named-content content-type="genus-species">Legionella pneumophila</named-content> Resilience in Water
title_fullStr	<italic toggle="yes">csrR</italic>, a Paralog and Direct Target of CsrA, Promotes <named-content content-type="genus-species">Legionella pneumophila</named-content> Resilience in Water
title_full_unstemmed	<italic toggle="yes">csrR</italic>, a Paralog and Direct Target of CsrA, Promotes <named-content content-type="genus-species">Legionella pneumophila</named-content> Resilience in Water
title_sort	<italic toggle="yes">csrr</italic>, a paralog and direct target of csra, promotes <named-content content-type="genus-species">legionella pneumophila</named-content> resilience in water
publisher	American Society for Microbiology
publishDate	2015
url	https://doaj.org/article/068d6c9c8cc443ae84333ee56d704238
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<italic toggle="yes">csrR</italic>, a Paralog and Direct Target of CsrA, Promotes <named-content content-type="genus-species">Legionella pneumophila</named-content> Resilience in Water

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