Role of phosphoglucosamine mutase on virulence properties of Streptococcus mutans.

Introduction: Streptococcus mutans has been strongly implicated as the principal etiological agent in dental caries. As a gram-positive bacterium, S. mutans has a thick and compact cell wall to maintain the cell shape and protect the cells against mechanical or osmotic damage. Previous studies have proved that peptidoglycan is the main component of the cell wall involved in the autolysis or biofilm formation processes.

Methods: In this study, we investigated the gene SMU.1426c in the amino-sugar metabolism pathway of S. mutans UA159, which encodes phosphoglucosamine mutase (GlmM). The glmM gene that functions in the biosynthesis of peptidoglycan has been well investigated in Escherichia coli. Here a glmM mutant strain of S. mutans UA159 was constructed and several virulence properties were investigated.

Results: The mutant devoid of the glmM gene displayed long chains, reduced growth rate and increased autolysis. Biofilm formation by the mutant was found to be attenuated.

Conclusion: These results proved that peptidoglycan biosynthesis plays an important part in a series of bacterial morphologies. The glmM gene may have a constructive role in the virulence properties of S. mutans.