title: An AfsK/AfsR system involved in the response of aerial mycelium formation to glucose in Streptomyces griseus.
abstract: In Streptomyces coelicolor A3(2), a protein serine/threonine kinase (AfsK) and its target protein (AfsR) control secondary metabolism. AfsK and AfsR homologues (AfsK-g and AfsR-g) from Streptomyces griseus showed high end-to-end similarity in amino acid sequence with the respective S. coelicolor A3(2) proteins, as determined by cloning and nucleotide sequencing. AfsK-g and a fusion protein between AfsK-g and thioredoxin (TRX-AfsK-g) produced in high yield as inclusion bodies in Escherichia coli were solubilized with urea, purified by column chromatography and then refolded to an active form by dialysis to gradually remove the urea. AfsR-g was also fused to glutathione S-transferase (GST-AfsR-g); the fusion product in the soluble fraction in E. coli was purified. Incubation of AfsK-g or TRX-AfsK-g in the presence of [gamma-32P]ATP yielded autophosphorylated products containing phosphoserine and phosphothreonine residues. In addition, TRX-AfsK-g phosphorylated serine and threonine residues of GST-AfsR-g in the presence of [gamma-32P]ATP. Disruption of chromosomal afsK-g had no effect on A-factor or streptomycin production, irrespective of the culture conditions. The afsK-g disruptants did not form aerial mycelium or spores on media containing glucose at concentrations higher than 1%, but did form spores on mannitol- and glycerol-containing media; this suggests that afsK-g is essential for morphogenesis in the presence of glucose. Introduction of afsK-g restored aerial mycelium formation in the disruptants. The phenotype of afsR-g disruptants was similar to that of afsK-g disruptants; introduction of afsR-g restored the defect in aerial mycelium formation on glucose-containing medium. Thus the AfsK/AfsR system in S. griseus is conditionally needed for morphological differentiation, whereas in S. coelicolor A3(2) it is conditionally involved in secondary metabolism.
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan1.
authors.forename: Takashi
authors.initials: T
authors.lastname: Umeyama
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan1.
authors.forename: Ping-Chin
authors.initials: PC
authors.lastname: Lee
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan1.
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 113-8657, Japan1.
authors.forename: Sueharu
authors.initials: S
authors.lastname: Horinouchi
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000032:analysis; D004268:DNA-Binding Proteins; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism*; D008969:Molecular Sequence Data; D019606:Phosphoamino Acids / Q000032:analysis; D010766:Phosphorylation; D010957:Plasmids / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D011995:Recombination, Genetic; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D015398:Signal Transduction; D015719:Single-Strand Specific DNA and RNA Endonucleases / Q000378:metabolism; D013305:Streptomyces griseus / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D014157:Transcription Factors; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D019606:Phosphoamino Acids; D011994:Recombinant Proteins; D014157:Transcription Factors; C066581:AfsR protein, Streptomyces coelicolor; D017346:Protein Serine-Threonine Kinases; D015719:Single-Strand Specific DNA and RNA Endonucleases; D005947:Glucose