Premium
The SloR metalloregulator is involved in the Streptococcus mutans oxidative stress response
Author(s) -
Crepps S.C.,
Fields E.E.,
Galan D.,
Corbett J.P.,
Von Hasseln E.R.,
Spatafora G.A.
Publication year - 2016
Publication title -
molecular oral microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 77
eISSN - 2041-1014
pISSN - 2041-1006
DOI - 10.1111/omi.12147
Subject(s) - streptococcus mutans , biology , virulence , microbiology and biotechnology , gene , oxidative stress , bacteria , genetics , biochemistry
Summary SloR, a 25‐ kD a metalloregulatory protein in Streptococcus mutans modulates the expression of multiple genes, including the slo ABC operon that encodes essential Mn 2+ transport and genes that promote cariogenesis. In this study, we report on SloC‐ and SloR‐deficient strains of S. mutans ( GMS 284 and GMS 584, respectively) that demonstrate compromised survivorship compared with their UA 159 wild‐type progenitor and their complemented strains ( GMS 285 and GMS 585, respectively), when challenged with streptonigrin and/or in growth competition experiments. The results of streptonigrin assays revealed significantly larger zones of inhibition for GMS 584 than for either UA 159 or GMS 585, indicating weakened S. mutans survivorship in the absence of SloR. Competition assays revealed a compromised ability for GMS 284 and GMS 584 to survive peroxide challenge compared with their SloC‐ and SloR‐proficient counterparts. These findings are consistent with a role for SloC and SloR in S. mutans aerotolerance. We also predicted differential expression of oxidative stress tolerance genes in GMS 584 versus UA 159 and GMS 585 when grown aerobically. The results of quantitative RT ‐ PCR experiments revealed S. mutans sod , tpx , and sloC expression that was upregulated in GMS 584 compared with UA 159 and GMS 585, indicating that the impact of oxidative stress on S. mutans is more severe in the absence of SloR than in its presence. The results of electrophoretic mobility shift assays indicate that SloR does not bind to the sod or tpx promoter regions directly, implicating intermediaries that may arbitrate the SloR response to oxidative stress.