In Silico and MS/MS-Based Approaches to Investigate Protein-Protein Interaction Networks in Staphylococcus Aureus Biofilm

Staphylococcus aureus is a Gram-positive pathogen inhabiting soft tissues like the epidermis and nasal cavity. Currently, there is limited knowledge of the protein-protein interaction (PPI) networks in S. aureus biofilm. The present study aimed to characterize S. aureus proteins and their interaction networks using an in silico approach and to identify the proteins expressed in S. aureus biofilm using tandem mass spectrometry. Initially, a preliminary characterization of the PPI networks in S. aureus was conducted using the STRING 12.0 database. Subsequently, S. aureus biofilm was developed in a 6-well microplate and harvested at 6 h, 12 h, 18 h, and 24 h. The expression of proteins in S. aureus biofilm was determined using a combination of one-dimensional SDS-PAGE and HPLC-ESI-MS/MS. The in silico results demonstrated that 147 biological processes, 46 molecular functions, 17 cellular components, and 15 biological pathways were significantly enriched (p <0.05) in the PPI networks of S. aureus. S. aureus biofilm proteins identified from the SDS-PAGE gel bands, such as L-lactate dehydrogenase (quinone), chaperone protein DnaK, and serine hydroxymethyltransferase, corroborated the findings obtained from the preliminary in silico work. In conclusion, the formation of biofilm by S. aureus may involve complex PPI networks. (author)