The proposed research aims to investigate the genetic and biochemical mechanisms of gene regulation in Streptococcus mutans through the irvA-dependent pathway. The goals of this project will be achieved in three aims by: 1) Analyzing the mechanism of irvA induction 2) Identifying the IrvA regulon 3) Characterizing the genetic regulators that comprise the irvA-dependent pathway. 1) To analyze the mechanism of irvA induction, we will perform detailed biochemical studies of key residues of SMu1275 to determine how its endogenous autocleavage capacity can modulate its ability to control irvA expression. 2) To identify the IrvA regulon, we will employ chromatin immunoprecipitation and microarray (ChIP-chip). Using specially designed Affymetrix Genechips(R), we will be able to detect most or all of the IrvA binding sites in vivo. Transcription analysis of these genes will determine the role of IrvA as a transcription regulator of genes associated with stress and virulence related phenotypes. 3) To characterize the genetic regulators of the irvA-dependent pathway, we will first identify the genes that are capable of inducing irvA. Genetic analyses will then examine the role of irvA as a mediator of stress and virulence related phenotypes in these strains. Finally, genes coregulated with the irvA-dependent pathway will be identified. The goal of this project is to use the irvA-dependent pathway as a model to examine the connection between stress adaptation and the regulation of important virulence factors of Streptococcus mutans. Since the long-term persistence of S. mutans requires the coordination of stress response mechanisms and virulence factor gene expression, these data may yield new insights into S. mutans cariogenicity.

Public Health Relevance

Dental caries is the most common human bacterial disease and is largely correlated with the overgrowth of Streptococcus mutans. Since this organism's ability to cause disease requires careful coordination of its stress response and virulence, these studies may yield novel treatment strategies to control the pathogenesis of S. mutans.

National Institute of Health (NIH)
National Institute of Dental & Craniofacial Research (NIDCR)
Research Project (R01)
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Oral, Dental and Craniofacial Sciences Study Section (ODCS)
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Lunsford, Dwayne
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University of Oklahoma Health Sciences Center
Schools of Dentistry
Oklahoma City
United States
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Merritt, Justin; Senpuku, Hidenobu; Kreth, Jens (2016) Let there be bioluminescence: development of a biophotonic imaging platform for in situ analyses of oral biofilms in animal models. Environ Microbiol 18:174-90
Itzek, A; Chen, Z; Merritt, J et al. (2016) Effect of salivary agglutination on oral streptococcal clearance by human polymorphonuclear neutrophil granulocytes. Mol Oral Microbiol :
Esteban Florez, Fernando Luis; Hiers, Rochelle Denise; Smart, Kristin et al. (2016) Real-time assessment of Streptococcus mutans biofilm metabolism on resin composite. Dent Mater 32:1263-9
Zhou, P; Liu, J; Merritt, J et al. (2015) A YadA-like autotransporter, Hag1 in Veillonella atypica is a multivalent hemagglutinin involved in adherence to oral streptococci, Porphyromonas gingivalis, and human oral buccal cells. Mol Oral Microbiol 30:269-79
Chen, Xi; Liu, Nan; Khajotia, Sharukh et al. (2015) RNases J1 and J2 are critical pleiotropic regulators in Streptococcus mutans. Microbiology 161:797-806
Kreth, Jens; Liu, Nan; Chen, Zhiyun et al. (2015) RNA regulators of host immunity and pathogen adaptive responses in the oral cavity. Microbes Infect 17:493-504
Liu, Nan; Niu, Guoqing; Xie, Zhoujie et al. (2015) The Streptococcus mutans irvA gene encodes a trans-acting riboregulatory mRNA. Mol Cell 57:179-90
Merritt, Justin; Chen, Zhiyun; Liu, Nan et al. (2014) Posttranscriptional regulation of oral bacterial adaptive responses. Curr Oral Health Rep 1:50-58
Yoneda, Saori; Loeser, Brandon; Feng, Joseph et al. (2014) Ubiquitous sialometabolism present among oral fusobacteria. PLoS One 9:e99263
Xie, Zhoujie; Qi, Fengxia; Merritt, Justin (2013) Development of a tunable wide-range gene induction system useful for the study of streptococcal toxin-antitoxin systems. Appl Environ Microbiol 79:6375-84

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