title: Organisation and functions of the actVA region of the actinorhodin biosynthetic gene cluster of Streptomyces coelicolor.
abstract: Sequence analysis of the actVA region of the actinorhodin biosynthetic gene cluster of Streptomyces coelicolor revealed a succession of six open reading frames (ORFs), all running in the same direction and extending over 5.32 kb. The protein product of actVA-ORF1 strongly resembles that of another gene, elsewhere in the act cluster (actII-ORF2), which codes for a trans-membrane protein previously implicated in actinorhodin export from the mycelium. This suggests that the two gene products may co-operate in actinorhodin export, perhaps being sufficient for self-protection of the organism against suicide. At least four of the other five ORFs are implicated in the control of the C-6 and C-8 ring-hydroxylation reactions, lacking in actVA mutants, that occur at middle to late stages in the actinorhodin biosynthetic pathway. This conclusion was reached by genetic mapping of actVA mutants to actVA-ORF3 and -ORF5 (and perhaps -ORF4), and by the finding of strong resemblances between the protein products of actVA-ORF2 and -ORF6 and the products of genes of the oxytetracycline or tetracenomycin gene clusters that have been implicated in ring-hydroxylation reactions in the biosynthesis of these other aromatic polyketide antibiotics.
authors.affiliation: John Innes Institute, John Innes Centre, Norwich, UK.
authors.forename: J L
authors.initials: JL
authors.lastname: Caballero
authors.forename: E
authors.initials: E
authors.lastname: Martinez
authors.forename: F
authors.initials: F
authors.lastname: Malpartida
authors.forename: D A
authors.initials: DA
authors.lastname: Hopwood
mesh_terms: D000595:Amino Acid Sequence; D000880:Anthraquinones / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D001483:Base Sequence; D003001:Cloning, Molecular; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D016366:Open Reading Frames; D010957:Plasmids; D015183:Restriction Mapping; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism; D000095622:Benzoisochromanequinones
chemical_list: D000880:Anthraquinones; D000900:Anti-Bacterial Agents; C013390:actinorhodin; D000095622:Benzoisochromanequinones