Activation of the Staphylococcus aureus intramembrane sensing histidine kinase SaeS via intramembrane interaction with the bacterially encoded small protein ScrA

ABSTRACT Two-component systems represent a fundamental sense-response mechanism in bacterial cells and often play important roles in critical processes such as quorum sensing, antibiotic tolerance, and virulence. Much has been learned about the role/activity of response regulator proteins, and their...

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Main Authors: Marcus A. Wittekind, Ian R. Monk, Ryan W. Steere, Emily G. Sudnick, Donald Holzschu, Padraig Deighan, Timothy P. Stinear, Ronan K. Carroll
Format: Article
Language:English
Published: American Society for Microbiology 2025-07-01
Series:mBio
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Online Access:https://journals.asm.org/doi/10.1128/mbio.01531-25
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author Marcus A. Wittekind
Ian R. Monk
Ryan W. Steere
Emily G. Sudnick
Donald Holzschu
Padraig Deighan
Timothy P. Stinear
Ronan K. Carroll
author_facet Marcus A. Wittekind
Ian R. Monk
Ryan W. Steere
Emily G. Sudnick
Donald Holzschu
Padraig Deighan
Timothy P. Stinear
Ronan K. Carroll
author_sort Marcus A. Wittekind
collection DOAJ
description ABSTRACT Two-component systems represent a fundamental sense-response mechanism in bacterial cells and often play important roles in critical processes such as quorum sensing, antibiotic tolerance, and virulence. Much has been learned about the role/activity of response regulator proteins, and their impact on gene expression can be monitored using techniques such as RNAseq and ChIP-seq. In contrast, sensor histidine kinases (HKs) remain poorly understood. In most cases, neither the stimulating signal nor the precise mechanism of action is known. This is particularly true for intramembrane sensing HKs (IM-HKs), which sense signals within the bacterial cell membrane. In this study, we show that ScrA, a bacterially encoded transmembrane protein and potent activator of the SaeRS two-component system, interacts directly with the IM-HK SaeS. We demonstrate that the interaction occurs between the transmembrane domains of both proteins and identify three ScrA amino acid residues that are important for this interaction. These results demonstrate that accessory proteins can play an important role in modulating the activity of bacterial two-component systems.IMPORTANCEBacterial pathogens sense environmental stimuli to enable adaptation to new niches, with two-component systems (TCS) playing an important role in this process. TCS consist of a sensor protein that detects a specific signal (often a change in environment), and a response protein that carries out a cellular response (typically altering gene expression). The precise signals that activate TCS are poorly understood, but in general, they are thought to emanate from outside the bacterial cell. Here, we demonstrate that a small membrane protein produced by Staphylococcus aureus can play a direct role in the activation of the SaeRS TCS, which plays an essential role in S. aureus infection. This represents a novel mechanism of activation for a bacterial TCS.
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spelling doaj-art-fac6ea503023447c8e6c19856c2b76712025-08-20T03:28:41ZengAmerican Society for MicrobiologymBio2150-75112025-07-0116710.1128/mbio.01531-25Activation of the Staphylococcus aureus intramembrane sensing histidine kinase SaeS via intramembrane interaction with the bacterially encoded small protein ScrAMarcus A. Wittekind0Ian R. Monk1Ryan W. Steere2Emily G. Sudnick3Donald Holzschu4Padraig Deighan5Timothy P. Stinear6Ronan K. Carroll7Department of Biological Sciences, Ohio University, Athens, Ohio, USADepartment of Microbiology and Immunology, Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, Victoria, AustraliaDepartment of Biological Sciences, Ohio University, Athens, Ohio, USADepartment of Biological Sciences, Ohio University, Athens, Ohio, USADepartment of Biological Sciences, Ohio University, Athens, Ohio, USADepartment of Biology, Emmanuel College, Boston, Massachusetts, USADepartment of Microbiology and Immunology, Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, Victoria, AustraliaDepartment of Biological Sciences, Ohio University, Athens, Ohio, USAABSTRACT Two-component systems represent a fundamental sense-response mechanism in bacterial cells and often play important roles in critical processes such as quorum sensing, antibiotic tolerance, and virulence. Much has been learned about the role/activity of response regulator proteins, and their impact on gene expression can be monitored using techniques such as RNAseq and ChIP-seq. In contrast, sensor histidine kinases (HKs) remain poorly understood. In most cases, neither the stimulating signal nor the precise mechanism of action is known. This is particularly true for intramembrane sensing HKs (IM-HKs), which sense signals within the bacterial cell membrane. In this study, we show that ScrA, a bacterially encoded transmembrane protein and potent activator of the SaeRS two-component system, interacts directly with the IM-HK SaeS. We demonstrate that the interaction occurs between the transmembrane domains of both proteins and identify three ScrA amino acid residues that are important for this interaction. These results demonstrate that accessory proteins can play an important role in modulating the activity of bacterial two-component systems.IMPORTANCEBacterial pathogens sense environmental stimuli to enable adaptation to new niches, with two-component systems (TCS) playing an important role in this process. TCS consist of a sensor protein that detects a specific signal (often a change in environment), and a response protein that carries out a cellular response (typically altering gene expression). The precise signals that activate TCS are poorly understood, but in general, they are thought to emanate from outside the bacterial cell. Here, we demonstrate that a small membrane protein produced by Staphylococcus aureus can play a direct role in the activation of the SaeRS TCS, which plays an essential role in S. aureus infection. This represents a novel mechanism of activation for a bacterial TCS.https://journals.asm.org/doi/10.1128/mbio.01531-25two component systemsignal transductionhistidine kinaseintramembraneSaeS
spellingShingle Marcus A. Wittekind
Ian R. Monk
Ryan W. Steere
Emily G. Sudnick
Donald Holzschu
Padraig Deighan
Timothy P. Stinear
Ronan K. Carroll
Activation of the Staphylococcus aureus intramembrane sensing histidine kinase SaeS via intramembrane interaction with the bacterially encoded small protein ScrA
mBio
two component system
signal transduction
histidine kinase
intramembrane
SaeS
title Activation of the Staphylococcus aureus intramembrane sensing histidine kinase SaeS via intramembrane interaction with the bacterially encoded small protein ScrA
title_full Activation of the Staphylococcus aureus intramembrane sensing histidine kinase SaeS via intramembrane interaction with the bacterially encoded small protein ScrA
title_fullStr Activation of the Staphylococcus aureus intramembrane sensing histidine kinase SaeS via intramembrane interaction with the bacterially encoded small protein ScrA
title_full_unstemmed Activation of the Staphylococcus aureus intramembrane sensing histidine kinase SaeS via intramembrane interaction with the bacterially encoded small protein ScrA
title_short Activation of the Staphylococcus aureus intramembrane sensing histidine kinase SaeS via intramembrane interaction with the bacterially encoded small protein ScrA
title_sort activation of the staphylococcus aureus intramembrane sensing histidine kinase saes via intramembrane interaction with the bacterially encoded small protein scra
topic two component system
signal transduction
histidine kinase
intramembrane
SaeS
url https://journals.asm.org/doi/10.1128/mbio.01531-25
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