Regulation of the lic operon of Bacillus subtilis and characterization of potential phosphorylation sites of the LicR regulator protein by site-directed mutagenesis

• Published in: Journal of bacteriology Vol. 181; no. 16; pp. 4995 - 5003
• Main Authors: Tobisch, S, Stülke, J, Hecker, M
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01.08.1999
• Subjects: Bacillus subtilis; Bacillus subtilis - genetics; Bacillus subtilis - metabolism; Bacteria; Bacterial Proteins; Bacteriology; Cellular biology; Chromosome Mapping; DNA-Binding Proteins - genetics; DNA-Directed RNA Polymerases - genetics; Gene Expression Regulation, Bacterial - drug effects; Gene Expression Regulation, Enzymologic - drug effects; Genetic Complementation Test; Genetics and Molecular Biology; Glucans - pharmacology; Glycoside Hydrolases - genetics; Glycoside Hydrolases - metabolism; Lac Operon; Mutagenesis, Site-Directed; Mutation; Operon - genetics; Phosphoenolpyruvate Sugar Phosphotransferase System - chemistry; Phosphoenolpyruvate Sugar Phosphotransferase System - genetics; Phosphoenolpyruvate Sugar Phosphotransferase System - metabolism; Phosphorylation; Plasmids; Promoter Regions, Genetic; Protein Structure, Tertiary; Proteins; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Regulation; Repressor Proteins - genetics; Sigma Factor - genetics; Trans-Activators - genetics; Trans-Activators - metabolism
• ISSN: 0021-9193; 1098-5530
• DOI: 10.1128/JB.181.16.4995-5003.1999

The lic operon of Bacillus subtilis is required for the transport and degradation of oligomeric beta-glucosides, which are produced by extracellular enzymes on substrates such as lichenan or barley glucan. The lic operon is transcribed from a sigma(A)-dependent promoter and is inducible by lichenan, lichenan hydrolysate, and cellobiose. Induction of the operon requires a DNA sequence with dyad symmetry located immediately upstream of the licBCAH promoter. Expression of the lic operon is positively controlled by the LicR regulator protein, which contains two potential helix-turn-helix motifs, two phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) regulation domains (PRDs), and a domain similar to PTS enzyme IIA (EIIA). The activity of LicR is stimulated by modification (probably phosphorylation) of both PRD-I and PRD-II by the general PTS components and is negatively regulated by modification (probably phosphorylation) of its EIIA domain by the specific EII(Lic) in the absence of oligomeric beta-glucosides. This was shown by the analysis of licR mutants affected in potential phosphorylation sites. Moreover, the lic operon is subject to carbon catabolite repression (CCR). CCR takes place via a CcpA-dependent mechanism and a CcpA-independent mechanism in which the general PTS enzyme HPr is involved.