title: Critical roles of arginine in growth and biofilm development by Streptococcus gordonii.
abstract: Streptococcus gordonii is an oral commensal and an early coloniser of dental plaque. In vitro, S. gordonii is conditionally auxotrophic for arginine in monoculture but biosynthesises arginine when coaggregated with Actinomyces oris. Here, we investigated the arginine-responsive regulatory network of S. gordonii and the basis for conditional arginine auxotrophy. ArcB, the catabolic ornithine carbamoyltransferase involved in arginine degradation, was also essential for arginine biosynthesis. However, arcB was poorly expressed following arginine depletion, indicating that arcB levels may limit S. gordonii arginine biosynthesis. Arginine metabolism gene expression was tightly co-ordinated by three ArgR/AhrC family regulators, encoded by argR, ahrC and arcR genes. Microarray analysis revealed that > 450 genes were regulated in response to rapid shifts in arginine concentration, including many genes involved in adhesion and biofilm formation. In a microfluidic salivary biofilm model, low concentrations of arginine promoted S. gordonii growth, whereas high concentrations (> 5 mM arginine) resulted in dramatic reductions in biofilm biomass and changes to biofilm architecture. Collectively, these data indicate that arginine metabolism is tightly regulated in S. gordonii and that arginine is critical for gene regulation, cellular growth and biofilm formation. Manipulating exogenous arginine concentrations may be an attractive approach for oral biofilm control.
authors: School of Dental Sciences, Newcastle University, Newcastle upon Tyne, UK.
authors: Nicholas S
authors: NS
authors: Jakubovics
authors: School of Dental Sciences, Newcastle University, Newcastle upon Tyne, UK.
authors: Jill C
authors: JC
authors: Robinson
authors: School of Public Health, Department of Epidemiology, University of Michigan, Ann Arbor, MI, USA.
authors: Derek S
authors: DS
authors: Samarian
authors: School of Public Health, Department of Epidemiology, University of Michigan, Ann Arbor, MI, USA.
authors: Ethan
authors: E
authors: Kolderman
authors: School of Dental Sciences, Newcastle University, Newcastle upon Tyne, UK.
authors: Sufian A
authors: SA
authors: Yassin
authors: School of Public Health, Department of Epidemiology, University of Michigan, Ann Arbor, MI, USA.
authors: Deepti
authors: D
authors: Bettampadi
authors: Bioinformatics Support Unit, Newcastle University, Newcastle upon Tyne, UK.
authors: Matthew
authors: M
authors: Bashton
authors: School of Public Health, Department of Epidemiology, University of Michigan, Ann Arbor, MI, USA.
authors: Alexander H
authors: AH
authors: Rickard
mesh_terms: D000190:Actinomyces / Q000378:metabolism; D001120:Arginine / Q000096:biosynthesis / Q000378:metabolism*; D001422:Bacterial Adhesion / Q000502:physiology; D018441:Biofilms / Q000254:growth & development*; D008969:Molecular Sequence Data; D009954:Ornithine Carbamoyltransferase / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D054773:Streptococcus gordonii / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*
chemical_list: D012329:RNA, Bacterial; D012333:RNA, Messenger; D001120:Arginine; D009954:Ornithine Carbamoyltransferase