Cervimycin-Resistant Staphylococcus aureus Strains Display Vancomycin-Intermediate Resistant Phenotypes

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Antibiotic resistance is a growing global health threat, necessitating new therapeutic strategies.
• Cervimycins, natural products from Streptomyces tendae, exhibit activity against multidrug-resistant staphylococci and vancomycin-resistant enterococci.
• Understanding cervimycin's mode of action is crucial for developing novel antibacterial therapies.

Purpose of the Study:

• To elucidate the mode of action of cervimycin antibiotics.
• To identify genetic determinants of resistance to cervimycin in Staphylococcus aureus.
• To investigate the phenotypic consequences of cervimycin resistance.

Main Methods:

• Generation and characterization of cervimycin-resistant (CmR) Staphylococcus aureus mutants.
• Whole-genome sequencing to identify mutations in CmR strains.
• In vitro and in vivo assays to assess protein activity and bacterial resistance.
• Transcriptomic and proteomic analyses to investigate global gene expression changes.

Main Results:

• CmR mutants frequently harbored combined mutations in the essential histidine kinase WalK and heat shock genes ClpP, ClpC, or DnaK.
• Mutations in ClpP or ClpC abolished protease activity, conferring resistance.
• Mutations in WalK decreased kinase activity and induced a vancomycin-intermediate resistant (VISA) phenotype with altered cell wall structure and growth rate.
• Massive transcriptomic and proteomic alterations were observed, particularly in heat shock, metal ion homeostasis, and carbohydrate metabolism pathways.

Conclusions:

• Cervimycin resistance in S. aureus is primarily mediated by mutations in the WalK kinase and the Clp protease system (ClpP/ClpC).
• Cervimycin resistance is associated with a VISA phenotype, suggesting cervimycin targets cell wall metabolism or the Clp protease system.
• These findings provide critical insights into cervimycin's mode of action and highlight potential targets for new antibacterial drug development.