title: Biochemical activities of the absA two-component system of Streptomyces coelicolor.
abstract: The AbsA1 sensor kinase and its cognate response regulator AbsA2 are important regulators of antibiotic synthesis in Streptomyces coelicolor. While certain point mutations in absA1 reduce or eliminate the synthesis of several antibiotics, null mutations in these genes bring about enhanced antibiotic synthesis. We show here that AbsA1, which is unusual in sequence and structure, is both an AbsA2 kinase and an AbsA2 approximately P phosphatase. The half-life of AbsA2 approximately P in solution is 68.6 min, consistent with a role in maintaining a relatively stable state of transcriptional repression or activation. We find that mutations in the absA locus that enhance antibiotic synthesis impair AbsA2 kinase activity and that mutations that repress antibiotic synthesis impair AbsA2 approximately P phosphatase activity. These results support a model in which the phosphorylation state of AbsA2 is determined by the balance of the kinase and phosphatase activities of AbsA1 and where AbsA2 approximately P represses antibiotic biosynthetic genes either directly or indirectly.
authors.affiliation: Department of Biochemistry & Biomedical Sciences, McMaster University Health Sciences Centre, 1200 Main St. W., Hamilton, Ontario, Canada L8N 3Z5.
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Sheeler
authors.forename: Susan V
authors.initials: SV
authors.lastname: MacMillan
authors.forename: Justin R
authors.initials: JR
authors.lastname: Nodwell
mesh_terms: D000222:Adaptation, Physiological; D000900:Anti-Bacterial Agents / Q000096:biosynthesis; D001426:Bacterial Proteins / Q000378:metabolism* / Q000502:physiology*; D004252:DNA Mutational Analysis; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000502:physiology*; D011494:Protein Kinases / Q000502:physiology*; D012097:Repressor Proteins / Q000378:metabolism; D015398:Signal Transduction; D048372:Streptomyces coelicolor / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: C433524:AbsA2 protein, Streptomyces coelicolor; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases