Project description:We have previously shown that responses of the oral bacterium Streptococcus gordonii to arginine are co-ordinated by three paralogous regulators: ArgR, ArgR and AhrC. This set of experiments was designed to assess the effects of the ArgR gene regulator on global gene expression in Streptococcus gordonii under high arginine or following a shift to no arginine.
Project description:We have previously shown that responses of the oral bacterium Streptococcus gordonii to arginine are co-ordinated by three paralogous regulators: ArcR, ArgR and AhrC. This set of experiments was designed to assess the effects of the AhrC gene regulator on global gene expression in Streptococcus gordonii under high arginine or following a shift to no arginine.
Project description:We have previously shown that responses of the oral bacterium Streptococcus gordonii to arginine are co-ordinated by three paralogous regulators: ArcR, ArgR and AhrC. This set of experiments was designed to assess the effects of the ArcR gene regulator on global gene expression in Streptococcus gordonii under high arginine or following a shift to no arginine.
Project description:Oral streptococci, including Streptococcus gordonii, and Actinomyces naeslundii, are consistently found to be the most abundant bacteria in the early stages of dental plaque accumulation. These organisms interact physically (coaggregate) in vitro and in vivo. We hypothesized that coaggregation between S. gordonii and A. naeslundii leads to changes in gene expression in the partner organisms. Furthermore, we predicted that coaggregation-induced changes in phenotype contribute to the success of streptococci and actinomyces in dental plaque. To assess the responses of S. gordonii to coaggregation with A. naeslundii, RNA was extracted from S. gordonii cells 3 h after inducing coaggregation with A. naeslundii or from equivalent S. gordonii monocultures. The two RNA populations were reverse transcribed and compared by competitive hybridization with an S. gordonii genomic microarray. The most striking feature of the response to coaggregation was a profound change in expression of S. gordonii genes involved in arginine biosynthesis and transport. Subsequent experiments demonstrated that coaggregation with A. naeslundii stabilizes arginine biosynthesis in S. gordonii and enables growth under low-arginine conditions, such as those present in human saliva. Keywords: Cell-cell interaction
