Functional Analysis of VicK Kinase Activity in Streptococcus Mutans

Objective To investigate the regulatory function on physiology and virulence of VicK kinase activity in Streptococcus mutans. Methods PCR ligation mutagenesis was used to construct a vicK knock-out mutant, and kinase activity abolished VicK was expressed by a streptococcal vector in this vicK null mutant. Colony morphology, overnight culture, biofilm formation and gene expression involved in biofilm formation were analyzed. ΔVicK, strains harboring a complemented wild-type vicK, and a vector without insert were used as controls. Results Colonies of VicKH217A were smoother and more elevated than that of wild-type UA159 and complementary strain SMCVicK; cells from VicKH217A overnight culture coaggregated on the bottom of glass tubes; no obvious alteration was observed in VicKH217A biofilm; expressions of gbpB, ftf, gtfD were repressed while gtfB/C were up-regulated (PStreptococcus mutans.