Analysis of Streptococcus mutans Proteins by Two-Dimensional Gel Electrophoresis

Objectives: Streptococcus mutans is a primary pathogen of dental caries and also plays an important role in the infective endocarditis. It has been suggested that Surface-associated proteins are important causative agents of this organism. For a better understanding of all these factors, we try to identify the most surface-associated proteins of Streptococcus mutans and to investigate differences in protein expression between strains from caries-active and caries-free patients. Methods: Surface-associated proteins of Streptococcus mutans separated from different caries experience people were extracted from cells grown in batch culture, separated by gel electrophoresis, excised, digested with trypsin, and analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry and liquid chromatography-tandem mass spectrometry. Results: Over 40 proteins were identified, these included some well-known surface proteins, such as cell surface antigen SpaP, cell wall-associated protein precursor WapA, glucosyltransferase-I, glucosyltransferase-SI and so on. We also found some ATPase, 30S and 50S ribosomal protein and some other hypothetical protein express. Six of the proteins identified were differentially expressed when coming to the different strains, which separated from different caries experience people. Conclusions: This study has extended the range of Streptococcus mutans proteins known to be expressed at the cell surface. Further investigations are required to ascertain their functions and determine how their expressions influence the virulence of this organism.