title: Biosynthesis of actinorhodin and related antibiotics: discovery of alternative routes for quinone formation encoded in the act gene cluster.
abstract: All known benzoisochromanequinone (BIQ) biosynthetic gene clusters carry a set of genes encoding a two-component monooxygenase homologous to the ActVA-ORF5/ActVB system for actinorhodin biosynthesis in Streptomyces coelicolor A3(2). Here, we conducted molecular genetic and biochemical studies of this enzyme system. Inactivation of actVA-ORF5 yielded a shunt product, actinoperylone (ACPL), apparently derived from 6-deoxy-dihydrokalafungin. Similarly, deletion of actVB resulted in accumulation of ACPL, indicating a critical role for the monooxygenase system in C-6 oxygenation, a biosynthetic step common to all BIQ biosyntheses. Furthermore, in vitro, we showed a quinone-forming activity of the ActVA-ORF5/ActVB system in addition to that of a known C-6 monooxygenase, ActVA-ORF6, by using emodinanthrone as a model substrate. Our results demonstrate that the act gene cluster encodes two alternative routes for quinone formation by C-6 oxygenation in BIQ biosynthesis.
authors.affiliation: National Food Research Institute, Kannondai, Tsukuba 305-8642, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Okamoto
authors.forename: Takaaki
authors.initials: T
authors.lastname: Taguchi
authors.forename: Kozo
authors.initials: K
authors.lastname: Ochi
authors.forename: Koji
authors.initials: K
authors.lastname: Ichinose
mesh_terms: D000880:Anthraquinones / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D010084:Oxidation-Reduction; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D048372:Streptomyces coelicolor / Q000201:enzymology* / Q000235:genetics; D000095622:Benzoisochromanequinones
chemical_list: D000880:Anthraquinones; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D006899:Mixed Function Oxygenases; D011994:Recombinant Proteins; C013390:actinorhodin; D000095622:Benzoisochromanequinones