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Updated: May 7, 2026
08:58
Isolation and Identification of Waterborne Antibiotic-Resistant Bacteria and Molecular Characterization of their Antibiotic Resistance Genes
Published on: March 3, 2023
IreB, a Ser/Thr kinase substrate, influences antimicrobial resistance in Enterococcus faecalis
Cherisse L Hall1, Michael Tschannen, Elizabeth A Worthey
1Department of Microbiology and Molecular Genetics.
Antimicrobial Agents and Chemotherapy
|October 2, 2013
Summary
Enterococcus faecalis
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Antibiotic Resistance
Background:
- Enterococcus faecalis causes significant hospital-acquired infections.
- Intrinsic cephalosporin resistance in E. faecalis is not fully understood.
- The Ser/Thr kinase IreK and phosphatase IreP regulate this resistance.
Purpose of the Study:
- Identify factors downstream of IreK involved in cephalosporin resistance.
- Elucidate the function of the conserved protein IreB.
- Investigate the role of IreB phosphorylation in antibiotic resistance.
Main Methods:
- Genetic screening for suppressor mutations in a ΔireK mutant.
- Biochemical analysis of IreB phosphorylation by IreK and IreP.
- Site-directed mutagenesis of IreB phosphorylation sites.
Main Results:
- Suppressor mutations were identified in IreB, a gene of unknown function.
- IreB negatively regulates cephalosporin resistance.
- IreB is phosphorylated by IreK and IreP on conserved threonine residues.
- Mutations impairing IreB phosphorylation reduce cephalosporin resistance.
Conclusions:
- IreB is a key component in the IreK-IreP signaling pathway for cephalosporin resistance.
- IreK-dependent phosphorylation modulates IreB activity, contributing to antibiotic resistance.
- This study elucidates the function of the previously uncharacterized IreB protein.
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