All Stressed Out? Investigating a Role for SloR in the Streptococcus Mutans Oxidative Stress Response, Poster 51

Streptococcus mutans is the main etiological agent of dental caries, an infectious disease that disproportionately affects individuals from lower socioeconomic groups. To persist on the dentition, S. mutans must respond and... [ view full abstract ]

Streptococcus mutans is the main etiological agent of dental caries, an infectious disease that disproportionately affects individuals from lower socioeconomic groups. To persist on the dentition, S. mutans must respond and adapt to challenges posed by neighboring members of the plaque biofilm. Oxidative stress, one of these challenges, contributes to the accumulation of reactive oxygen species (ROS) that can degrade essential macromolecules in the cell. Recently, the Spatafora laboratory implicated SloR in S. mutans oxidative stress tolerance. In the present study, we performed competition assays with S. mutans UA159 and SloC-deficient mutant derivative (GMS284). The results of these studies reveal hypersensitivity of GMS284 to S. gordonii H2O2 production. We attribute this sensitivity to compromised Mn2+ transport in GMS284, which attenuates S. mutans Mn-SOD activity. These findings validate sloC as an oxidative stress gene and lend further support to a role for SloR in the S. mutans oxidative stress response. To determine if SpxA1, a transcriptional regulator of S. mutans oxidative stress, is subject to SloR control, we performed EMSAs, which implicated SpxA1 as a putative intermediary of the SloR-regulated oxidative stress response. This work is significant because it can inform rational drug design aimed at alleviating S. mutans-induced dental caries.