The Streptococcus mutans GlnR protein exhibits an increased affinity for the glnRA operon promoter when bound to GlnK

• Published in: Brazilian journal of medical and biological research Vol. 44; no. 12; pp. 1202 - 1208
• Main Authors: Castellen, P, Rego, F G M, Portugal, M E G, Benelli, E M
• Format: Journal Article
• Language: English
• Published: Brazil Associação Brasileira de Divulgação Científica 01-12-2011
• Subjects: Ammonium; Animals; Bacillus subtilis; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Base Sequence; BIOLOGY; Data processing; DNA; DNA, Bacterial - genetics; Electrophoretic mobility; Gene Expression Regulation, Bacterial - genetics; Gene regulation; GlnK; GlnR; GlnR protein; Gram-positive bacteria; MEDICINE, RESEARCH & EXPERIMENTAL; Metabolism; Molecular Sequence Data; Nitrogen; Nitrogen - metabolism; Operon - genetics; Operons; PII-type protein; Promoter Regions, Genetic - genetics; Promoters; Protein turnover; Rats; Rats, Wistar; Signal transduction; Streptococcus mutans; Streptococcus mutans - genetics; Streptococcus mutans - metabolism; Transcription; Transcriptional regulator; virulence factors; GlnR; Transcriptional regulator; PII-type protein; GlnK; Streptococcus mutans
• ISSN: 0100-879X; 1414-431X; 1414-431X; 0100-879X
• DOI: 10.1590/S0100-879X2011007500138

The control of nitrogen metabolism in pathogenic Gram-positive bacteria has been studied in a variety of species and is involved with the expression of virulence factors. To date, no data have been reported regarding nitrogen metabolism in the odontopathogenic species Streptococcus mutans. GlnR, which controls nitrogen assimilation in the related bacterial species, Bacillus subtilis, was assessed in S. mutans for its DNA and protein binding activity. Electrophoretic mobility shift assay of the S. mutans GlnR protein indicated that GlnR binds to promoter regions of the glnRA and amtB-glnK operons. Cross-linking and pull-down assays demonstrated that GlnR interacts with GlnK, a signal transduction protein that coordinates the regulation of nitrogen metabolism. Upon formation of this stable complex, GlnK enhances the affinity of GlnR for the glnRA operon promoter. These results support an involvement of GlnR in transcriptional regulation of nitrogen metabolism-related genes and indicate that GlnK relays information regarding ammonium availability to GlnR.