Collectively, these results further suggest that Rex in S. Relative to UA159, JB314 displayed major defects in biofilm formation, with a decrease of more than 50-fold in biomass after 48-hours. Consistent with a role in oxidative stress tolerance, hydrogen peroxide challenge assays showed that the Rex-deficient mutant, TW239, and the Rex/GuaA double mutant, JB314, were more susceptible to hydrogen peroxide killing than the wildtype, UA159. mutans can function as an activator in response to intracellular NADH/NAD + level, although the exact binding site for activator Rex remains unclear. Electrophoretic mobility shift assays showed that recombinant Rex bound promoters of target genes avidly and specifically, including those down-regulated in response to more » Rex-deficiency, and that the ability of recombinant Rex to bind to selected promoters was modulated by NADH and NAD +. mutans is co-transcribed as an operon with downstream guaA, encoding a putative glutamine amidotransferase. mutans to have increased susceptibility to oxidative stress, aberrations in glucan production, and poor biofilm formation. We have previously shown that Streptococcus mutans, the primary causative agent of dental caries, alters its transcriptome upon Rex-deficiency and renders S. The Rex repressor has been implicated in regulation of central carbon and energy metabolism in Gram-positive bacteria. Publication Date: Research Org.: Los Alamos National Lab (LANL), Los Alamos, NM (United States) Sponsoring Org.: USDOE National Nuclear Security Administration (NNSA) National Institutes of Health (NIH) National Institute of Dental and Craniofacial Research (NIDCR) OSTI Identifier: 1628034 Grant/Contract Number: AC52-06NA25396 DE19452 DE25348 Resource Type: Journal Article: Accepted Manuscript Journal Name: Frontiers in Cellular and Infection Microbiology Additional Journal Information: Journal Volume: 7 Journal ID: ISSN 2235-2988 Publisher: Frontiers Research Foundation Country of Publication: United States Language: English Subject: Immunology = , Biofilm Research Labs, Levy Center for Oral Health, Department of Orthodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, (United States).Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, NY, (United States).Department of Comprehensive Dentistry and Biomaterials, Louisiana State University Health Sciences Center, New Orleans, LA, (United States). Center of Oral and Craniofacial Biology, Louisiana State University Health Sciences Center, New Orleans, LA (United States).of Microbiology, Immunology and Parasitology of Comprehensive Dentistry and Biomaterials, Dept. Center of Oral and Craniofacial Biology, Dept. Louisiana State University Health Sciences Center, New Orleans, LA, (United States).mutans and oral lactobacilli are species-specific and may have significant impact on cariogenic potential of the community. These results further suggest that interactions between S. Among the down-regulated genes were those for GtfB and alternative sigma factor SigX. The up-regulated genes include those for superoxide dismutase, NADH oxidase, and members of the mutanobactin biosynthesis cluster. casei as either up- or down-regulated when compared to those grown more » alone. When analyzed by RNA-seq, more than 134 genes were identified in S. rhamnosus was increased by 2-log ( P 1-log ( P 1-log ( P < 0.001), but drastically reduced the survival rates following exposure to hydrogen peroxide ( P < 0.001), as compared to the respective mono-species cultures. The results showed that lactobacilli did not form good biofilms when grown alone, although differences existed between different species. This study used mixed-species models to analyze biofilm formation by major groups of oral lactobacilli, including L. Like Streptococcus mutans, lactobacilli are commonly isolated from carious sites, although their exact role in caries development remains unclear.
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