Quantitative cell surface proteome profiling for SigB-dependent protein expression in the human pathogen...

Area of Science:

• Microbiology
• Proteomics
• Molecular Biology

Background:

• Staphylococcus aureus virulence factors are often cell surface-associated or secreted.
• Understanding the cell surface proteome is crucial for S. aureus pathophysiology.
• The alternative sigma factor sigma B (SigB) is hypothesized to influence surface protein expression.

Purpose of the Study:

• To perform a global and quantitative analysis of S. aureus cell surface-associated proteins.
• To investigate the impact of the sigma B (SigB) factor on the expression of these surface proteins.
• To identify novel SigB-modulated surface proteins and potential virulence factors.

Main Methods:

• Utilized (14)N/(15)N metabolic labeling, biotinylation, and GeLC-MS/MS for quantitative proteomic analysis.
• Compared the methicillin-resistant S. aureus (MRSA) wild-type strain COL with its sigB mutant.
• Analyzed proteins from both growing and non-growing cell states.

Main Results:

• Quantified a total of 296 cell surface-associated proteins.
• Identified 49 surface-associated proteins modulated by SigB, with 21 previously known.
• Observed more down-regulated (31) than up-regulated (18) proteins in the sigB mutant, and discovered 28 novel SigB-influenced surface proteins.

Conclusions:

• SigB significantly modulates the S. aureus surface proteome, impacting numerous cell surface proteins.
• This study expands the known repertoire of SigB-regulated surface proteins and potential virulence factors.
• The findings provide new insights into S. aureus virulence mechanisms and SigB regulation.