Characterization of cis- Acting Sites Controlling Arginine Deiminase Gene Expression in Streptococcus gordonii

Abstract

The arginine deiminase system (ADS) is responsible for the production of ornithine, CO 2 , ammonia, and ATP from arginine. The ADS of the oral bacterium Streptococcus gordonii plays major roles in physiologic homeostasis, acid tolerance, and oral biofilm ecology. To further our understanding of the transcriptional regulation of the ADS (arc) operon, the binding of the ArcR transcriptional activator, which governs expression of the ADS in response to arginine, was investigated by DNase I protection and gel mobility shift assays. An ArcR binding sequence was found that was 27 bp in length and had little sequence similarity to binding sites of other arginine metabolism regulators. The presence of arginine at physiologically relevant concentrations enhanced the binding of ArcR to its target. Using cat fusions, various deletion and substitution mutations within the putative ArcR footprint were shown to cause dramatic reductions in expression from the arcA promoter in vivo, confirming that the 27-bp sequence is required for optimal expression and induction of the ADS by arginine. Mutation of two putative catabolite response elements (CREs) within the arc promoter region showed that both CREs contribute to catabolite repression. A thorough understanding of the regulation of the ADS in S. gordonii and related organisms is needed to develop ways to exploit arginine catabolism for the control of oral diseases. Identification of the ArcR and CcpA binding sites lays the foundation for a more complete understanding of the complex interactions of multiple regulatory proteins with elements in the arc promoter region.

CcpA-Dependent and -Independent Control of Beta-Galactosidase Expression in Streptococcus pneumoniae Occurs via Regulation of an Upstream Phosphotransferase System-Encoding Operon

“…Here, regulation involves both CcpA and ArcR, which is an activator of the ADS. The two regulators share overlapping binding sequences in the promoter regions, which results in CcpA inhibition of RNA polymerase binding, as well as ArcR binding (47). The results of previous studies of S. pneumoniae suggested that CcpA regulates both ␤-galactosidase and ␣-glucosidase but is not involved in glucose repression of either of these enzymes (11).…”

“…For multiple streptococcal species (9,11,16,33,47) and Lactobacillus casei (12), CcpA (also referred to as RegM [11,33]) is not responsible for all catabolite repression. For example, in Streptococcus mutans, disruption of ccpA results in increased glucose repression of enzymes involved in carbohydrate utilization (33).…”

“…For example, in Streptococcus mutans, disruption of ccpA results in increased glucose repression of enzymes involved in carbohydrate utilization (33). In Streptococcus gordonii, the arginine deaminase system (ADS) involves multiple levels of regulation (9,47). Here, regulation involves both CcpA and ArcR, which is an activator of the ADS.…”

Regulation of Gene Expression in a Mixed-Genus Community: Stabilized Arginine Biosynthesis inStreptococcus gordoniiby Coaggregation withActinomyces naeslundii

“…2B). The expression of arcB in S. gordonii is thought to be directed by the promoter upstream of arcA, which is subject to multiple regulatory controls: it is activated by ArcR in the presence of arginine and by Flp under anaerobic conditions and is repressed by CcpA in response to glucose or other phosphotransferase transport system (PTS) sugars (9,58). Therefore, at low concentrations of arginine and in the presence of oxygen and glucose, the arcA promoter is inactive and arcB is poorly expressed.…”

Oral Arginine Metabolism May Decrease the Risk for Dental Caries in Children

“…In oral biofilms, arginine is mainly metabolized by the arginine deiminase system (ADS) of oral bacteria, which yields citrulline, ornithine, CO 2 , ATP, and ammonia (Burne and Marquis, 2000). A substantial knowledge base about the physiology and genetics of the ADS in oral bacteria has been established (Marquis et al, 1987;Casiano-Colon and Marquis, 1988;Burne et al, 1991;Curran et al, 1998;Dong et al, 2004;Griswold et al, 2004;Zeng et al, 2006;Liu and Burne, 2009), but the role of arginine metabolism in oral ecology and oral health has not been thoroughly studied in humans. The main goal of this study was to explore the relationship between ADS activity and caries experience in children.…”