Elucidation of Copper Chaperone, CopZ, Mediated Regulation of Biofilm in Streptococcus mutans

Objectives: Tooth decay is a multifactorial disease, caused by the right combination of sugar intake, poor dental hygiene, and cariogenic bacteria. Streptococcus mutans is the most associated with tooth decay which is attributed to the ability of S. mutans to form a tenacious biofilm and inhibit oral commensal species. Recently, our lab has shown that copper chaperone CopZ is essential to these virulence factors, however, the mechanism is largely unknown.
Methods: Utilized qRT-PCR, Isothermal titration calorimetry, confocal laser scanning microscopy, and growth inhibition assays.
Results: The copZ mutant has reduced biofilm, potentially due to downregulation of several biofilm related genes such as GbpD and GtfB.We found that compared to the parent strain and the other cop operon mutants, the copZ mutant dramatically secretes hypothetical protein SMU_739c. A mutation of SMU_739c led to defective biofilm formation and biofilm structure.
Conclusions: The CopZ mutant has a global effect on S. mutans biofilm related genes. The secretion of SMU_739c by the copZ mutant could suggest a potential interaction related to biofilm formation. Elucidation of the role of CopZ mediated biofilm regulation could reveal a novel regulatory pathway for biofilm formation.