title: RibR, a possible regulator of the Bacillus subtilis riboflavin biosynthetic operon, in vivo interacts with the 5'-untranslated leader of rib mRNA.
abstract: RibR is a minor cryptic flavokinase (EC 2.7.1.26) of the Gram-positive bacterium Bacillus subtilis with an unknown cellular function. The flavokinase activity appears to be localized to the N-terminal domain of the protein. Using the yeast three-hybrid system, it was shown that RibR specifically interacts in vivo with the nontranslated wild-type leader of the mRNA of the riboflavin biosynthetic operon. This interaction is lost partially when a leader containing known cis-acting deregulatory mutations in the so-called RFN element is tested. The RFN element is a sequence within the rib-leader mRNA reported to serve as a receptor for an FMN-dependent 'riboswitch'. In RibR itself, interaction was localized to the carboxy-terminate part of the protein, a segment of unknown function that does not show similarity to other proteins in the public databases. Analysis of a ribR-defective strain revealed a mild deregulation with respect to flavin (riboflavin, FMN and FAD) biosynthesis. The results indicate that the RNA-binding protein RibR may be involved in the regulation of the rib genes.
authors.affiliation: Institute for Technical Microbiology, Mannheim University of Applied Sciences, Windeckstr, Mannheim, Germany.
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Higashitsuji
authors.forename: Annemarie
authors.initials: A
authors.lastname: Angerer
authors.forename: Sabine
authors.initials: S
authors.lastname: Berghaus
authors.forename: Birgit
authors.initials: B
authors.lastname: Hobl
authors.forename: Matthias
authors.initials: M
authors.lastname: Mack
mesh_terms: D020121:5' Untranslated Regions / Q000378:metabolism*; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005415:Flavins / Q000096:biosynthesis; D009154:Mutation; D009876:Operon; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D025941:Protein Interaction Mapping; D012333:RNA, Messenger / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D020121:5' Untranslated Regions; D001426:Bacterial Proteins; D005415:Flavins; D012333:RNA, Messenger; D017853:Phosphotransferases (Alcohol Group Acceptor); C022532:riboflavin kinase