Cyclic Enterobacterial Common Antigen Maintains the Outer Membrane Permeability Barrier of <named-content content-type="genus-species">Escherichia coli</named-content> in a Manner Controlled by YhdP

ABSTRACT Gram-negative bacteria have an outer membrane (OM) impermeable to many toxic compounds that can be further strengthened during stress. In Enterobacteriaceae, the envelope contains enterobacterial common antigen (ECA), a carbohydrate-derived moiety conserved throughout Enterobacteriaceae, th...

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Autores principales:	Angela M. Mitchell, Tharan Srikumar, Thomas J. Silhavy
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2018
Materias:	ECA Enterobacteriaceae Escherichia coli YhdP enterobacterial common antigen outer membrane Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/01a1c4071d6746baba160c568f8e5273
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spelling	oai:doaj.org-article:01a1c4071d6746baba160c568f8e52732021-11-15T16:00:15ZCyclic Enterobacterial Common Antigen Maintains the Outer Membrane Permeability Barrier of <named-content content-type="genus-species">Escherichia coli</named-content> in a Manner Controlled by YhdP10.1128/mBio.01321-182150-7511https://doaj.org/article/01a1c4071d6746baba160c568f8e52732018-09-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.01321-18https://doaj.org/toc/2150-7511ABSTRACT Gram-negative bacteria have an outer membrane (OM) impermeable to many toxic compounds that can be further strengthened during stress. In Enterobacteriaceae, the envelope contains enterobacterial common antigen (ECA), a carbohydrate-derived moiety conserved throughout Enterobacteriaceae, the function of which is poorly understood. Previously, we identified several genes in Escherichia coli K-12 responsible for an RpoS-dependent decrease in envelope permeability during carbon-limited stationary phase. For one of these, yhdP, a gene of unknown function, deletion causes high levels of both vancomycin and detergent sensitivity, independent of growth phase. We isolated spontaneous suppressor mutants of yhdP with loss-of-function mutations in the ECA biosynthesis operon. ECA biosynthesis gene deletions suppressed envelope permeability from yhdP deletion independently of envelope stress responses and interactions with other biosynthesis pathways, demonstrating suppression is caused directly by removing ECA. Furthermore, yhdP deletion changed cellular ECA levels and yhdP was found to co-occur phylogenetically with the ECA biosynthesis operon. Cells make three forms of ECA: ECA lipopolysaccharide (LPS), an ECA chain linked to LPS core; ECA phosphatidylglycerol, a surface-exposed ECA chain linked to phosphatidylglycerol; and cyclic ECA, a cyclized soluble ECA molecule found in the periplasm. We determined that the suppression of envelope permeability with yhdP deletion is caused specifically by the loss of cyclic ECA, despite lowered levels of this molecule found with yhdP deletion. Furthermore, removing cyclic ECA from wild-type cells also caused changes to OM permeability. Our data demonstrate cyclic ECA acts to maintain the OM permeability barrier in a manner controlled by YhdP. IMPORTANCE Enterobacterial common antigen (ECA) is a surface antigen made by all members of Enterobacteriaceae, including many clinically relevant genera (e.g., Escherichia, Klebsiella, Yersinia). Although this surface-exposed molecule is conserved throughout Enterobacteriaceae, very few functions have been ascribed to it. Here, we have determined that the periplasmic form of ECA, cyclic ECA, plays a role in maintaining the outer membrane permeability barrier. This activity is controlled by a protein of unknown function, YhdP, and deletion of yhdP damages the OM permeability barrier in a cyclic ECA-dependent manner, allowing harmful molecules such as antibiotics into the cell. This role in maintenance of the envelope permeability barrier is the first time a phenotype has been described for cyclic ECA. As the Gram-negative envelope is generally impermeable to antibiotics, understanding the mechanisms through which the barrier is maintained and antibiotics are excluded may lead to improved antibiotic delivery.Angela M. MitchellTharan SrikumarThomas J. SilhavyAmerican Society for MicrobiologyarticleECAEnterobacteriaceaeEscherichia coliYhdPenterobacterial common antigenouter membraneMicrobiologyQR1-502ENmBio, Vol 9, Iss 4 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	ECA Enterobacteriaceae Escherichia coli YhdP enterobacterial common antigen outer membrane Microbiology QR1-502
spellingShingle	ECA Enterobacteriaceae Escherichia coli YhdP enterobacterial common antigen outer membrane Microbiology QR1-502 Angela M. Mitchell Tharan Srikumar Thomas J. Silhavy Cyclic Enterobacterial Common Antigen Maintains the Outer Membrane Permeability Barrier of <named-content content-type="genus-species">Escherichia coli</named-content> in a Manner Controlled by YhdP
description	ABSTRACT Gram-negative bacteria have an outer membrane (OM) impermeable to many toxic compounds that can be further strengthened during stress. In Enterobacteriaceae, the envelope contains enterobacterial common antigen (ECA), a carbohydrate-derived moiety conserved throughout Enterobacteriaceae, the function of which is poorly understood. Previously, we identified several genes in Escherichia coli K-12 responsible for an RpoS-dependent decrease in envelope permeability during carbon-limited stationary phase. For one of these, yhdP, a gene of unknown function, deletion causes high levels of both vancomycin and detergent sensitivity, independent of growth phase. We isolated spontaneous suppressor mutants of yhdP with loss-of-function mutations in the ECA biosynthesis operon. ECA biosynthesis gene deletions suppressed envelope permeability from yhdP deletion independently of envelope stress responses and interactions with other biosynthesis pathways, demonstrating suppression is caused directly by removing ECA. Furthermore, yhdP deletion changed cellular ECA levels and yhdP was found to co-occur phylogenetically with the ECA biosynthesis operon. Cells make three forms of ECA: ECA lipopolysaccharide (LPS), an ECA chain linked to LPS core; ECA phosphatidylglycerol, a surface-exposed ECA chain linked to phosphatidylglycerol; and cyclic ECA, a cyclized soluble ECA molecule found in the periplasm. We determined that the suppression of envelope permeability with yhdP deletion is caused specifically by the loss of cyclic ECA, despite lowered levels of this molecule found with yhdP deletion. Furthermore, removing cyclic ECA from wild-type cells also caused changes to OM permeability. Our data demonstrate cyclic ECA acts to maintain the OM permeability barrier in a manner controlled by YhdP. IMPORTANCE Enterobacterial common antigen (ECA) is a surface antigen made by all members of Enterobacteriaceae, including many clinically relevant genera (e.g., Escherichia, Klebsiella, Yersinia). Although this surface-exposed molecule is conserved throughout Enterobacteriaceae, very few functions have been ascribed to it. Here, we have determined that the periplasmic form of ECA, cyclic ECA, plays a role in maintaining the outer membrane permeability barrier. This activity is controlled by a protein of unknown function, YhdP, and deletion of yhdP damages the OM permeability barrier in a cyclic ECA-dependent manner, allowing harmful molecules such as antibiotics into the cell. This role in maintenance of the envelope permeability barrier is the first time a phenotype has been described for cyclic ECA. As the Gram-negative envelope is generally impermeable to antibiotics, understanding the mechanisms through which the barrier is maintained and antibiotics are excluded may lead to improved antibiotic delivery.
format	article
author	Angela M. Mitchell Tharan Srikumar Thomas J. Silhavy
author_facet	Angela M. Mitchell Tharan Srikumar Thomas J. Silhavy
author_sort	Angela M. Mitchell
title	Cyclic Enterobacterial Common Antigen Maintains the Outer Membrane Permeability Barrier of <named-content content-type="genus-species">Escherichia coli</named-content> in a Manner Controlled by YhdP
title_short	Cyclic Enterobacterial Common Antigen Maintains the Outer Membrane Permeability Barrier of <named-content content-type="genus-species">Escherichia coli</named-content> in a Manner Controlled by YhdP
title_full	Cyclic Enterobacterial Common Antigen Maintains the Outer Membrane Permeability Barrier of <named-content content-type="genus-species">Escherichia coli</named-content> in a Manner Controlled by YhdP
title_fullStr	Cyclic Enterobacterial Common Antigen Maintains the Outer Membrane Permeability Barrier of <named-content content-type="genus-species">Escherichia coli</named-content> in a Manner Controlled by YhdP
title_full_unstemmed	Cyclic Enterobacterial Common Antigen Maintains the Outer Membrane Permeability Barrier of <named-content content-type="genus-species">Escherichia coli</named-content> in a Manner Controlled by YhdP
title_sort	cyclic enterobacterial common antigen maintains the outer membrane permeability barrier of <named-content content-type="genus-species">escherichia coli</named-content> in a manner controlled by yhdp
publisher	American Society for Microbiology
publishDate	2018
url	https://doaj.org/article/01a1c4071d6746baba160c568f8e5273
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Cyclic Enterobacterial Common Antigen Maintains the Outer Membrane Permeability Barrier of <named-content content-type="genus-species">Escherichia coli</named-content> in a Manner Controlled by YhdP

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