Overexpression, purification and ligand interaction studies of intact membrane sensory kinases from enterococci: towards agonist and antagonist screening
type: CreativeWork
description: Two component signal transduction systems are of great importance in the regulation of expression of many virulence traits in bacteria and are a vital component of the way bacteria sense and respond to their environment. The sensor kinase component is generally membrane bound and is involved in detecting any changes to its environment through binding of a specific ligand signal, resulting in activation of its partner response regulator component and thereby bringing about a response which is usually a change in expression levels of specific gene sets. These regulatory systems are particularly important in controlling antibiotic resistances in enterococci. Enterococci are amongst the most significant agents of nosocomial infections in the UK. The present study involved an investigation of two membrane sensor kinases known to be involved in antibiotic resistance in enterococci: (1) VanSA, involved in type A resistance to vancomycin in Enterococcus faecium which involves high level of inducible resistance to both vancomycin and teicoplanin antibiotics. VanSAsenses an unknown signalling ligand, which may either be the glycopeptide antibiotics them selves or more indirect ligands such as cell wall intermediates that accumulate in response to antibiotic inhibition of its cell wall target sites. Upon activation, VanSa becomes phosphorylated and phosphorylates its response regulator (VanR), thereby activating downstream genes which produce the vancomycin resistance phenotype. The nature of the ligand is therefore unknown, and one of the aims of this study is to address this and to determine whether it is vancomycin itself or cell wall intermediates; and (2) EF3290 (HK05), which is part of the CroRS system in Enterococcus faecalis and which has been shown by knock out studies to be involved in intrinsic beta-lactam resistance in enterococci. The present study involved an in vitro approach using purified intact VanSa and EF3290 membrane proteins to investigate the nature of t…
abstract: Two component signal transduction systems are of great importance in the regulation of expression of many virulence traits in bacteria and are a vital component of the way bacteria sense and respond to their environment. The sensor kinase component is generally membrane bound and is involved in detecting any changes to its environment through binding of a specific ligand signal, resulting in activation of its partner response regulator component and thereby bringing about a response which is usually a change in expression levels of specific gene sets. These regulatory systems are particularly important in controlling antibiotic resistances in enterococci. Enterococci are amongst the most significant agents of nosocomial infections in the UK. The present study involved an investigation of two membrane sensor kinases known to be involved in antibiotic resistance in enterococci: (1) VanSA, involved in type A resistance to vancomycin in Enterococcus faecium which involves high level of inducible resistance to both vancomycin and teicoplanin antibiotics. VanSAsenses an unknown signalling ligand, which may either be the glycopeptide antibiotics them selves or more indirect ligands such as cell wall intermediates that accumulate in response to antibiotic inhibition of its cell wall target sites. Upon activation, VanSa becomes phosphorylated and phosphorylates its response regulator (VanR), thereby activating downstream genes which produce the vancomycin resistance phenotype. The nature of the ligand is therefore unknown, and one of the aims of this study is to address this and to determine whether it is vancomycin itself or cell wall intermediates; and (2) EF3290 (HK05), which is part of the CroRS system in Enterococcus faecalis and which has been shown by knock out studies to be involved in intrinsic beta-lactam resistance in enterococci. The present study involved an in vitro approach using purified intact VanSa and EF3290 membrane proteins to investigate the nature of t…
author: Pogson (Kelsall), Claire
keywords: C770 - Biophysical science
date published: 2013-06
date modified: 2026-07-24T01:35:53Z
provider: University of Central Lancashire
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Central Lancashire