title: A Streptomyces griseus gene (sgaA) suppresses the growth disturbance caused by high osmolality and a high concentration of A-factor during early growth.
abstract: A-factor (2-isocapryloyl-3R-hydroxymethyl-gamma-butyrolactone), produced in a growth-dependent manner, switches on secondary metabolite formation and morphological differentiation in Streptomyces griseus, presumably by binding to the A-factor receptor protein (ArpA)-DNA complex and releasing the repression caused by ArpA. In the A-factor-deficient mutant strain S. griseus HH1 a large deletion includes afsA which is required for A-factor production. Growth and aerial mycelium formation of strain HH1 on media containing high concentrations of sucrose, sorbitol, mannitol, KCl or NaCl was disturbed by the presence of a large amount of A-factor supplied either exogenously or by a high-copy-number plasmid carrying afsA. This disturbance did not occur on media of normal osmolality and was observed only when A-factor was supplied during the very early stage of growth, about 8 h after inoculation. In addition, neither the wild-type strain nor S. griseus KM7 defective in ArpA exhibited the disturbance. These observations suggest that the presence of a large amount of A-factor during the very early stage of growth, probably during the A-factor-sensitive stage, triggered abrupt and disordered expression of some genes. The effect was apparently mediated through ArpA in the A-factor regulatory cascade and disturbed the physiology of strain HH1 under high osmolality. A gene that suppressed the disturbance was identified 5.5 kb upstream of the afsA locus in the wild-type strain. The gene, named sgaA, encoded a protein of 264 aa with a calculated molecular mass of 28 kDa.
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Ando
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Ueda
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan.
authors.forename: Sueharu
authors.initials: S
authors.lastname: Horinouchi
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D002455:Cell Division / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D018628:Gene Dosage; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D016153:Genes, Suppressor; D006133:Growth Substances / Q000378:metabolism* / Q000494:pharmacology; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000235:genetics; D009997:Osmotic Pressure; D010957:Plasmids; D012097:Repressor Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013305:Streptomyces griseus / Q000235:genetics* / Q000254:growth & development*; D013307:Streptomycin / Q000096:biosynthesis
chemical_list: C108224:AfsA protein, Streptomyces griseus; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D006133:Growth Substances; D012097:Repressor Proteins; C108223:SgaA protein, Streptomyces griseus; C025035:A-factor (Streptomyces); D015107:4-Butyrolactone; D013307:Streptomycin