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Improved accuracy of cell surface shaving proteomics in Staphylococcus aureus using a false-positive control
Nestor Solis1, Martin R Larsen, Stuart J Cordwell
1School of Molecular and Microbial Biosciences, The University of Sydney, Australia.
Proteomics
|March 11, 2010
Summary
This study introduces a cell surface shaving technique to identify bacterial surface proteins for vaccine development. This method effectively distinguishes surface proteins from intracellular contaminants, aiding in the discovery of novel vaccine targets against Staphylococcus aureus.
Area of Science:
- Microbiology and Immunology
- Proteomics and Bioinformatics
Background:
- Identifying surface-exposed peptide epitopes on bacteria is crucial for novel vaccine discovery.
- Bacterial cell stability during proteolytic treatment can be compromised, leading to intracellular protein contamination.
- Staphylococcus aureus is a significant human pathogen with increasing antibiotic resistance, necessitating new therapeutic strategies.
Purpose of the Study:
- To develop and validate a cell surface "shaving" technique for identifying surface-exposed peptide epitopes on Staphylococcus aureus.
- To improve the accuracy of surface protein identification by mitigating intracellular protein contamination.
- To identify potential vaccine targets from the surface proteome of S. aureus.
Main Methods:
- Employed a cell surface "shaving" technique using trypsin or proteinase-K combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS).
- Implemented a "false-positive" control strategy involving incubation without protease to identify and subtract peptides from cell lysis.
- Analyzed and compared peptides identified by different proteases and the control group to determine surface-exposed proteins.
Main Results:
- Identified 42 predicted S. aureus COL surface proteins from 260 surface-exposed peptides.
- Trypsin and proteinase-K digests showed complementary results, identifying unique and overlapping surface proteins.
- The false-positive subtraction strategy enriched surface-exposed peptides in the trypsin dataset to approximately 80%.
- Key identified surface proteins included those associated with methicillin resistance (mecA, pls), autolysin, and extracellular matrix-binding protein Ebh.
Conclusions:
- The cell surface shaving strategy is a rapid and effective method for identifying surface-exposed peptide epitopes on S. aureus.
- This technique successfully distinguishes surface proteins from intracellular contaminants, enhancing the reliability of epitope discovery.
- The identified surface proteins, particularly those linked to antibiotic resistance, represent promising candidates for novel vaccine development against S. aureus.
