title: A small basic protein from the brz-brb operon is involved in regulation of bop transcription in Halobacterium salinarum.
abstract: BACKGROUND
  The halophilic archaeon Halobacterium salinarum expresses bacteriorhodopsin, a retinal-protein that allows photosynthetic growth. Transcription of the bop (bacterioopsin) gene is controlled by two transcription factors, Bat and Brz that induce bop when cells are grown anaerobically and under light.
  
  
  RESULTS
  A new gene was identified that is transcribed together with the brz gene that encodes a small basic protein designated as Brb (bacteriorhodopsin-regulating basic protein). The translation activity of the start codon of the brb gene was confirmed by BgaH reporter assays. In vivo site-directed mutagenesis of the brb gene showed that the Brb protein cooperates with Brz in the regulation of bop expression. Using a GFP reporter assay, it was demonstrated that Brb cooperates with both Brz and Bat proteins to activate bop transcription under phototrophic growth conditions.
  
  
  CONCLUSIONS
  The activation of the bop promoter was shown to be dependent not only on two major factors, Bat and Brz, but is also tuned by the small basic protein, Brb.
authors.affiliation: Max-Planck Institute of Biochemistry, Department of Membrane Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
authors.forename: Valery
authors.initials: V
authors.lastname: Tarasov
authors.forename: Rita
authors.initials: R
authors.lastname: Schwaiger
authors.forename: Katarina
authors.initials: K
authors.lastname: Furtwängler
authors.forename: Mike
authors.initials: M
authors.lastname: Dyall-Smith
authors.forename: Dieter
authors.initials: D
authors.lastname: Oesterhelt
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000235:genetics / Q000378:metabolism*; D001436:Bacteriorhodopsins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D019848:Gene Expression Regulation, Archaeal; D017930:Genes, Reporter; D019617:Halobacterium salinarum / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009876:Operon; D011401:Promoter Regions, Genetic; D012336:RNA, Ribosomal, 16S / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D019843:Archaeal Proteins; D012336:RNA, Ribosomal, 16S; D001436:Bacteriorhodopsins; C017827:bacterio-opsin