Stochastic Expression of Sae-Dependent Virulence Genes during <named-content content-type="genus-species">Staphylococcus aureus</named-content> Biofilm Development Is Dependent on SaeS

ABSTRACT The intricate process of biofilm formation in the human pathogen Staphylococcus aureus involves distinct stages during which a complex mixture of matrix molecules is produced and modified throughout the developmental cycle. Early in biofilm development, a subpopulation of cells detaches fro...

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Autores principales:	Elizabeth A. DelMain, Derek E. Moormeier, Jennifer L. Endres, Rebecca E. Hodges, Marat R. Sadykov, Alexander R. Horswill, Kenneth W. Bayles
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2020
Materias:	Staphylococcus aureus biofilms developmental biology gene regulation stochastic expression virulence factors Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/a518981338dd468c88d0f44327b410dc
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spelling	oai:doaj.org-article:a518981338dd468c88d0f44327b410dc2021-11-15T15:56:58ZStochastic Expression of Sae-Dependent Virulence Genes during <named-content content-type="genus-species">Staphylococcus aureus</named-content> Biofilm Development Is Dependent on SaeS10.1128/mBio.03081-192150-7511https://doaj.org/article/a518981338dd468c88d0f44327b410dc2020-02-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.03081-19https://doaj.org/toc/2150-7511ABSTRACT The intricate process of biofilm formation in the human pathogen Staphylococcus aureus involves distinct stages during which a complex mixture of matrix molecules is produced and modified throughout the developmental cycle. Early in biofilm development, a subpopulation of cells detaches from its substrate in an event termed “exodus” that is mediated by SaePQRS-dependent stochastic expression of a secreted staphylococcal nuclease, which degrades extracellular DNA within the matrix, causing the release of cells and subsequently allowing for the formation of metabolically heterogenous microcolonies. Since the SaePQRS regulatory system is involved in the transcriptional control of multiple S. aureus virulence factors, the expression of several additional virulence genes was examined within a developing biofilm by introducing fluorescent gene reporter plasmids into wild-type S. aureus and isogenic regulatory mutants and growing these strains in a microfluidic system that supplies the bacteria with a constant flow of media while simultaneously imaging developing biofilms in 5-min intervals. This study demonstrated that multiple virulence genes, including nuc, were expressed stochastically within a specialized subpopulation of cells in nascent biofilms. We demonstrated that virulence genes regulated by SaePQRS were stochastically expressed in nearly all strains examined whereas Agr-regulated genes were expressed more homogenously within maturing microcolonies. The commonly used Newman strain contains a variant of SaeS (SaeSP) that confers constitutive kinase activity to the protein and caused this strain to lack the stochastic expression pattern observed in other strain backgrounds. Importantly, repair of the SaeSP allele resulting in reversion to the well-conserved SaeSL allele found in other strains restored stochastic expression in this strain. IMPORTANCE Staphylococcus aureus is an important human pathogen capable of colonizing diverse tissue types and inducing severe disease in both immunocompromised and otherwise healthy individuals. Biofilm infections caused by this bacterial species are of particular concern because of their persistence, even in the face of intensive therapeutic intervention. The results of the current study demonstrate the stochastic nature of Sae-mediated virulence gene expression in S. aureus and indicate that this regulatory system may function as a “bistable switch” in a manner similar to that seen with regulators controlling competence gene expression in Bacillus subtilis and persister cell formation in Escherichia coli. The results of this study provide a new perspective on the complex mechanisms utilized by S. aureus during the establishment of infections.Elizabeth A. DelMainDerek E. MoormeierJennifer L. EndresRebecca E. HodgesMarat R. SadykovAlexander R. HorswillKenneth W. BaylesAmerican Society for MicrobiologyarticleStaphylococcus aureusbiofilmsdevelopmental biologygene regulationstochastic expressionvirulence factorsMicrobiologyQR1-502ENmBio, Vol 11, Iss 1 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	Staphylococcus aureus biofilms developmental biology gene regulation stochastic expression virulence factors Microbiology QR1-502
spellingShingle	Staphylococcus aureus biofilms developmental biology gene regulation stochastic expression virulence factors Microbiology QR1-502 Elizabeth A. DelMain Derek E. Moormeier Jennifer L. Endres Rebecca E. Hodges Marat R. Sadykov Alexander R. Horswill Kenneth W. Bayles Stochastic Expression of Sae-Dependent Virulence Genes during <named-content content-type="genus-species">Staphylococcus aureus</named-content> Biofilm Development Is Dependent on SaeS
description	ABSTRACT The intricate process of biofilm formation in the human pathogen Staphylococcus aureus involves distinct stages during which a complex mixture of matrix molecules is produced and modified throughout the developmental cycle. Early in biofilm development, a subpopulation of cells detaches from its substrate in an event termed “exodus” that is mediated by SaePQRS-dependent stochastic expression of a secreted staphylococcal nuclease, which degrades extracellular DNA within the matrix, causing the release of cells and subsequently allowing for the formation of metabolically heterogenous microcolonies. Since the SaePQRS regulatory system is involved in the transcriptional control of multiple S. aureus virulence factors, the expression of several additional virulence genes was examined within a developing biofilm by introducing fluorescent gene reporter plasmids into wild-type S. aureus and isogenic regulatory mutants and growing these strains in a microfluidic system that supplies the bacteria with a constant flow of media while simultaneously imaging developing biofilms in 5-min intervals. This study demonstrated that multiple virulence genes, including nuc, were expressed stochastically within a specialized subpopulation of cells in nascent biofilms. We demonstrated that virulence genes regulated by SaePQRS were stochastically expressed in nearly all strains examined whereas Agr-regulated genes were expressed more homogenously within maturing microcolonies. The commonly used Newman strain contains a variant of SaeS (SaeSP) that confers constitutive kinase activity to the protein and caused this strain to lack the stochastic expression pattern observed in other strain backgrounds. Importantly, repair of the SaeSP allele resulting in reversion to the well-conserved SaeSL allele found in other strains restored stochastic expression in this strain. IMPORTANCE Staphylococcus aureus is an important human pathogen capable of colonizing diverse tissue types and inducing severe disease in both immunocompromised and otherwise healthy individuals. Biofilm infections caused by this bacterial species are of particular concern because of their persistence, even in the face of intensive therapeutic intervention. The results of the current study demonstrate the stochastic nature of Sae-mediated virulence gene expression in S. aureus and indicate that this regulatory system may function as a “bistable switch” in a manner similar to that seen with regulators controlling competence gene expression in Bacillus subtilis and persister cell formation in Escherichia coli. The results of this study provide a new perspective on the complex mechanisms utilized by S. aureus during the establishment of infections.
format	article
author	Elizabeth A. DelMain Derek E. Moormeier Jennifer L. Endres Rebecca E. Hodges Marat R. Sadykov Alexander R. Horswill Kenneth W. Bayles
author_facet	Elizabeth A. DelMain Derek E. Moormeier Jennifer L. Endres Rebecca E. Hodges Marat R. Sadykov Alexander R. Horswill Kenneth W. Bayles
author_sort	Elizabeth A. DelMain
title	Stochastic Expression of Sae-Dependent Virulence Genes during <named-content content-type="genus-species">Staphylococcus aureus</named-content> Biofilm Development Is Dependent on SaeS
title_short	Stochastic Expression of Sae-Dependent Virulence Genes during <named-content content-type="genus-species">Staphylococcus aureus</named-content> Biofilm Development Is Dependent on SaeS
title_full	Stochastic Expression of Sae-Dependent Virulence Genes during <named-content content-type="genus-species">Staphylococcus aureus</named-content> Biofilm Development Is Dependent on SaeS
title_fullStr	Stochastic Expression of Sae-Dependent Virulence Genes during <named-content content-type="genus-species">Staphylococcus aureus</named-content> Biofilm Development Is Dependent on SaeS
title_full_unstemmed	Stochastic Expression of Sae-Dependent Virulence Genes during <named-content content-type="genus-species">Staphylococcus aureus</named-content> Biofilm Development Is Dependent on SaeS
title_sort	stochastic expression of sae-dependent virulence genes during <named-content content-type="genus-species">staphylococcus aureus</named-content> biofilm development is dependent on saes
publisher	American Society for Microbiology
publishDate	2020
url	https://doaj.org/article/a518981338dd468c88d0f44327b410dc
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Stochastic Expression of Sae-Dependent Virulence Genes during <named-content content-type="genus-species">Staphylococcus aureus</named-content> Biofilm Development Is Dependent on SaeS

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