SMU_1361c regulates the oxidative stress response of < em > Streptococcus mutans < /em >

Appl Environ Microbiol. 2024 Feb 1:e0187123. doi: 10.1128/aem.01871-23. Online ahead of print.ABSTRACTDental caries is the most common chronic infectious disease around the world and disproportionately affects the marginalized socioeconomic group. Streptococcus mutans, considered a primary etiological agent of caries, depends on the coordinated physiological response to tolerate the oxidative stress generated by commensal species within dental plaque, which is a critical aspect of its pathogenicity. Here, we identified and characterized a novel tetracycline repressor family regulator, SMU_1361c, which appears to be acquired by the bacteria via horizontal gene transfer. Surprisingly, smu_1361c functions as a negative transcriptional regulator to regulate gene expression outside its operon and is involved in the oxidative stress response of S. mutans. The smu_1361c overexpression strain UA159/pDL278-1361c was more susceptible to oxidative stress and less competitive against hydrogen peroxide generated by commensal species Streptococcus gordonii and Streptococcus sanguinis. Transcriptomics analysis revealed that smu_1361c overexpression resulted in the significant downregulation of 22 genes, mainly belonging to three gene clusters responsible for the oxidative stress response. The conversed DNA binding motif of SMU_1361c was determined by electrophoretic mobility shift and DNase I footprinting assay with purified SMU_1361c protein; therefore, smu_1361c is directly involved in ge...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Source Type: research