Genomic, Transcriptomic and Metabolomic Studies of Two Well-Characterized, Laboratory-Derived Vancomycin-Intermediate...

Area of Science:

• Microbiology
• Genomics
• Molecular Biology

Background:

• Vancomycin-intermediate Staphylococcus aureus (VISA) poses a significant treatment challenge.
• Understanding the genetic and molecular basis of VISA is crucial for developing new therapeutic strategies.

Purpose of the Study:

• To comprehensively analyze mutations and gene expression in two laboratory-selected VISA strains.
• To elucidate the molecular mechanisms underlying the VISA phenotype, including cell wall alterations and stress responses.

Main Methods:

• Whole-genome sequencing for mutation identification.
• Transcriptomic analysis to assess gene expression profiles.
• Metabolomic studies to investigate metabolic changes.

Main Results:

• Identified numerous mutations, many novel, in VISA strains, with higher mutation burden in the strain with higher vancomycin resistance.
• Observed significant alterations in cell wall metabolism, stress responses (including DNA damage repair), and downregulation of virulence factors.
• Detected hallmarks of the stringent response, increased cell wall precursor metabolites, and decreased polyamines, potentially facilitating mutation accumulation.

Conclusions:

• The VISA phenotype arises from diverse genetic and regulatory changes, not a single mechanism.
• Gene expression regulation and activated stress responses are critical components of the VISA state.
• Metabolic shifts, including altered amino acid and polyamine levels, contribute to VISA development and potential for further mutation.