Homeoviscous Adaptation of the <named-content content-type="genus-species">Acinetobacter baumannii</named-content> Outer Membrane: Alteration of Lipooligosaccharide Structure during Cold Stress

ABSTRACT To maintain optimal membrane dynamics, cells from all domains of life must acclimate to various environmental signals in a process referred to as homeoviscous adaptation. Alteration of the lipid composition is critical for maintaining membrane fluidity, permeability of the lipid bilayer, an...

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Autores principales:	Carmen M. Herrera, Bradley J. Voss, M. Stephen Trent
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2021
Materias:	Acinetobacter acylation acyltransferase cell envelope cold shock lipid A Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/101668c59f524abf840dfb0c763a72dd
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spelling	oai:doaj.org-article:101668c59f524abf840dfb0c763a72dd2021-11-10T18:37:51ZHomeoviscous Adaptation of the <named-content content-type="genus-species">Acinetobacter baumannii</named-content> Outer Membrane: Alteration of Lipooligosaccharide Structure during Cold Stress10.1128/mBio.01295-212150-7511https://doaj.org/article/101668c59f524abf840dfb0c763a72dd2021-08-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.01295-21https://doaj.org/toc/2150-7511ABSTRACT To maintain optimal membrane dynamics, cells from all domains of life must acclimate to various environmental signals in a process referred to as homeoviscous adaptation. Alteration of the lipid composition is critical for maintaining membrane fluidity, permeability of the lipid bilayer, and protein function under diverse conditions. It is well documented, for example, that glycerophospholipid content varies substantially in both Gram-negative and Gram-positive bacteria with changes in growth temperature. However, in the case of Gram-negative bacteria, far less is known concerning structural changes in lipopolysaccharide (LPS) or lipooligosaccharide (LOS) during temperature shifts. LPS/LOS is anchored at the cell surface by the highly conserved lipid A domain and localized in the outer leaflet of the outer membrane. Here, we identified a novel acyltransferase, termed LpxS, involved in the synthesis of the lipid A domain of Acinetobacter baumannii. A. baumannii is a significant, multidrug-resistant, opportunistic pathogen that is particularly difficult to clear from health care settings because of its ability to survive under diverse conditions. LpxS transfers an octanoate (C8:0) fatty acid, the shortest known secondary acyl chain reported to date, replacing a C12:0 fatty acid at the 2′ position of lipid A. Expression of LpxS was highly upregulated under cold conditions and likely increases membrane fluidity. Furthermore, incorporation of a C8:0 acyl chain under cold conditions increased the effectiveness of the outer membrane permeability barrier. LpxS orthologs are found in several Acinetobacter species and may represent a common mechanism for adaptation to cold temperatures in these organisms. IMPORTANCE To maintain cellular fitness, the composition of biological membranes must change in response to shifts in temperature or other stresses. This process, known as homeoviscous adaptation, allows for maintenance of optimal fluidity and membrane permeability. Here, we describe an enzyme that alters the fatty acid content of A. baumannii LOS, a major structural feature and key component of the bacterial outer membrane. Although much is known regarding how glycerophospholipids are altered during temperature shifts, our understanding of LOS or LPS alterations under these conditions is lacking. Our work identifies a cold adaptation mechanism in A. baumannii, a highly adaptable and multidrug-resistant pathogen.Carmen M. HerreraBradley J. VossM. Stephen TrentAmerican Society for MicrobiologyarticleAcinetobacteracylationacyltransferasecell envelopecold shocklipid AMicrobiologyQR1-502ENmBio, Vol 12, Iss 4 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Acinetobacter acylation acyltransferase cell envelope cold shock lipid A Microbiology QR1-502
spellingShingle	Acinetobacter acylation acyltransferase cell envelope cold shock lipid A Microbiology QR1-502 Carmen M. Herrera Bradley J. Voss M. Stephen Trent Homeoviscous Adaptation of the <named-content content-type="genus-species">Acinetobacter baumannii</named-content> Outer Membrane: Alteration of Lipooligosaccharide Structure during Cold Stress
description	ABSTRACT To maintain optimal membrane dynamics, cells from all domains of life must acclimate to various environmental signals in a process referred to as homeoviscous adaptation. Alteration of the lipid composition is critical for maintaining membrane fluidity, permeability of the lipid bilayer, and protein function under diverse conditions. It is well documented, for example, that glycerophospholipid content varies substantially in both Gram-negative and Gram-positive bacteria with changes in growth temperature. However, in the case of Gram-negative bacteria, far less is known concerning structural changes in lipopolysaccharide (LPS) or lipooligosaccharide (LOS) during temperature shifts. LPS/LOS is anchored at the cell surface by the highly conserved lipid A domain and localized in the outer leaflet of the outer membrane. Here, we identified a novel acyltransferase, termed LpxS, involved in the synthesis of the lipid A domain of Acinetobacter baumannii. A. baumannii is a significant, multidrug-resistant, opportunistic pathogen that is particularly difficult to clear from health care settings because of its ability to survive under diverse conditions. LpxS transfers an octanoate (C8:0) fatty acid, the shortest known secondary acyl chain reported to date, replacing a C12:0 fatty acid at the 2′ position of lipid A. Expression of LpxS was highly upregulated under cold conditions and likely increases membrane fluidity. Furthermore, incorporation of a C8:0 acyl chain under cold conditions increased the effectiveness of the outer membrane permeability barrier. LpxS orthologs are found in several Acinetobacter species and may represent a common mechanism for adaptation to cold temperatures in these organisms. IMPORTANCE To maintain cellular fitness, the composition of biological membranes must change in response to shifts in temperature or other stresses. This process, known as homeoviscous adaptation, allows for maintenance of optimal fluidity and membrane permeability. Here, we describe an enzyme that alters the fatty acid content of A. baumannii LOS, a major structural feature and key component of the bacterial outer membrane. Although much is known regarding how glycerophospholipids are altered during temperature shifts, our understanding of LOS or LPS alterations under these conditions is lacking. Our work identifies a cold adaptation mechanism in A. baumannii, a highly adaptable and multidrug-resistant pathogen.
format	article
author	Carmen M. Herrera Bradley J. Voss M. Stephen Trent
author_facet	Carmen M. Herrera Bradley J. Voss M. Stephen Trent
author_sort	Carmen M. Herrera
title	Homeoviscous Adaptation of the <named-content content-type="genus-species">Acinetobacter baumannii</named-content> Outer Membrane: Alteration of Lipooligosaccharide Structure during Cold Stress
title_short	Homeoviscous Adaptation of the <named-content content-type="genus-species">Acinetobacter baumannii</named-content> Outer Membrane: Alteration of Lipooligosaccharide Structure during Cold Stress
title_full	Homeoviscous Adaptation of the <named-content content-type="genus-species">Acinetobacter baumannii</named-content> Outer Membrane: Alteration of Lipooligosaccharide Structure during Cold Stress
title_fullStr	Homeoviscous Adaptation of the <named-content content-type="genus-species">Acinetobacter baumannii</named-content> Outer Membrane: Alteration of Lipooligosaccharide Structure during Cold Stress
title_full_unstemmed	Homeoviscous Adaptation of the <named-content content-type="genus-species">Acinetobacter baumannii</named-content> Outer Membrane: Alteration of Lipooligosaccharide Structure during Cold Stress
title_sort	homeoviscous adaptation of the <named-content content-type="genus-species">acinetobacter baumannii</named-content> outer membrane: alteration of lipooligosaccharide structure during cold stress
publisher	American Society for Microbiology
publishDate	2021
url	https://doaj.org/article/101668c59f524abf840dfb0c763a72dd
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Homeoviscous Adaptation of the <named-content content-type="genus-species">Acinetobacter baumannii</named-content> Outer Membrane: Alteration of Lipooligosaccharide Structure during Cold Stress

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