title: The structure of ActVA-Orf6, a novel type of monooxygenase involved in actinorhodin biosynthesis.
abstract: ActVA-Orf6 monooxygenase from Streptomyces coelicolor that catalyses the oxidation of an aromatic intermediate of the actinorhodin biosynthetic pathway is a member of a class of small monooxygenases that carry out oxygenation without the assistance of any of the prosthetic groups, metal ions or cofactors normally associated with activation of molecular oxygen. The overall structure is a ferredoxin-like fold with a novel dimeric assembly, indicating that the widely represented ferredoxin fold may sustain yet another functionality. The resolution (1.3 A) of the enzyme structure and its complex with substrate and product analogues allows us to visualize the mechanism of binding and activation of the substrate for attack by molecular oxygen, and utilization of two gates for the reaction components including a proton gate and an O(2)/H(2)O gate with a putative protein channel. This is the first crystal structure of an enzyme involved in the tailoring of a type II aromatic polyketide and illustrates some of the enzyme-substrate recognition features that may apply to a range of other enzymes involved in modifying a polyketide core structure.
authors.affiliation: Dipartimento di Scienze Biochimiche and CNR, Centro di Studi sulla Biologia Molecolare, Università di Roma 'La Sapienza', Piazzale A.Moro, 5, 00185 Roma, Italy.
authors.forename: Giuliano
authors.initials: G
authors.lastname: Sciara
authors.forename: Steven G
authors.initials: SG
authors.lastname: Kendrew
authors.forename: Adriana E
authors.initials: AE
authors.lastname: Miele
authors.forename: Neil G
authors.initials: NG
authors.lastname: Marsh
authors.forename: Luca
authors.initials: L
authors.lastname: Federici
authors.forename: Francesco
authors.initials: F
authors.lastname: Malatesta
authors.forename: Giuliana
authors.initials: G
authors.lastname: Schimperna
authors.forename: Carmelinda
authors.initials: C
authors.lastname: Savino
authors.forename: Beatrice
authors.initials: B
authors.lastname: Vallone
mesh_terms: D000595:Amino Acid Sequence; D000880:Anthraquinones / Q000737:chemistry / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006899:Mixed Function Oxygenases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010100:Oxygen / Q000378:metabolism; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013302:Streptomyces / Q000201:enzymology*; D000095622:Benzoisochromanequinones
chemical_list: D000880:Anthraquinones; D000900:Anti-Bacterial Agents; D006899:Mixed Function Oxygenases; D010100:Oxygen; C013390:actinorhodin; D000095622:Benzoisochromanequinones