title: Label-free quantitative proteomics analysis of antibiotic response in Staphylococcus aureus to oxacillin.
abstract: Methicillin-resistant Staphylococcus aureus (MRSA) is the leading cause of fatal bacterial infections in hospitals and has become a global health threat. Although the resistance mechanisms of β-lactam antibiotics have been studied for decades, there are few attempts at systems-wide investigations into how the bacteria respond to antibiotic stress. Spectral counting-based label-free quantitative proteomics has been applied to study global responses in MRSA and methicillin-susceptible S. aureus (MSSA) treated with subinhibitory doses of oxacillin, a model β-lactam antibiotic. We developed a simple and easily repeated sample preparation procedure that is effective for extracting surface-associated proteins. On average, 1025 and 1013 proteins were identified at a false discovery rate threshold of 0.01, for the untreated group of MRSA and MSSA. Upon treatment with oxacillin, 81 proteins (65 up-regulated, 16 down-regulated) were shown differentially expressed in MRSA (p < 0.05). In comparison, 225 proteins (162 up-regulated, 63 down-regulated) were shown differentially expressed in oxacillin-treated MSSA. β-Lactamase and penicillin-binding protein 2a were observed up-regulated uniquely in oxacillin-treated MRSA, which is consistent with the known β-lactam resistance mechanisms of S. aureus. More interestingly, the peptidoglycan biosynthesis pathway and the pantothenate and CoA biosynthesis pathway were found to be up-regulated in both oxacillin-treated MRSA and MSSA, and a series of energy metabolism pathways were up-regulated uniquely in oxacillin-treated MSSA. These new data offer a more complete view of the proteome changes in bacteria in response to the antibiotic. This report is the first in using label-free quantitative proteomics to study β-lactam antibiotic responses in S. aureus.
authors.affiliation: Department of Chemical and Biomolecular Engineering and ‡Division of Biomedical Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong.
authors.forename: Xiaofen
authors.initials: X
authors.lastname: Liu
authors.forename: Yingwei
authors.initials: Y
authors.lastname: Hu
authors.forename: Pei-Jing
authors.initials: PJ
authors.lastname: Pai
authors.forename: Daijie
authors.initials: D
authors.lastname: Chen
authors.forename: Henry
authors.initials: H
authors.lastname: Lam
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003065:Coenzyme A / Q000096:biosynthesis; D004734:Energy Metabolism / Q000187:drug effects; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D010068:Oxacillin / Q000494:pharmacology*; D010205:Pantothenic Acid / Q000096:biosynthesis; D046915:Penicillin-Binding Proteins / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D010457:Peptidoglycan / Q000096:biosynthesis; D020543:Proteome / Q000235:genetics* / Q000378:metabolism; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D018440:beta-Lactam Resistance / Q000187:drug effects* / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; D020543:Proteome; D010205:Pantothenic Acid; D001618:beta-Lactamases; D003065:Coenzyme A; D010068:Oxacillin