A novel quinone-forming monooxygenase family involved in modification of aromatic polyketides.
RppA is a type III polyketide synthase (PKS) that catalyzes condensation of five molecules of malonyl-CoA to form 1,3,6,8-tetrahydroxynaphthalene (THN). In Streptomyces antibioticus IFO13271 and several other Streptomyces species, an open reading frame, named momA, is present as a neighbor of rppA. MomA belonged to the "cupin" superfamily because it contained a set of two motifs that is responsible for binding one equivalent of metal ions. MomA catalyzed monooxygenation of the THN produced from malonyl-CoA by the action of RppA to form flaviolin. In addition, it used several polyketides as substrates and formed the corresponding quinones. MomA required redox-active transition metal ions (Ni(2+), Cu(2+), Fe(3+), Fe(2+), Mn(2+), and Co(2+)) for its activity, whereas it was inhibited by a redox-inert transition metal ion (Zn(2+)). MomA neither possessed any flavin prosthetic group nor required nicotinamide cofactors for monooxygenation, which shows that MomA as a member of the cupin superfamily is a novel monooxygenase. Consistent with the catalytic property of MomA, WhiE-ORFII showing similarity in amino acid sequence to MomA and containing a cupin domain also catalyzed monooxygenation of THN. whiE-ORFII is located immediately upstream of the "minimal PKS" gene within the whiE type II PKS gene cluster for biosynthesis of a gray spore pigment in Streptomyces coelicolor A3(2), and a number of whiE-ORFII homologues are present in the biosynthetic gene cluster for polyketides of type II in various Streptomyces species. These findings show that a novel class of quinone-forming monooxygenases is involved in modification of aromatic polyketides synthesized by PKSs of types II and III.
Funa
Nobutaka
N
Department of Biotechnology, Graduate School of Agriculture and Life Sciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
Funabashi
Masanori
M
Yoshimura
Etsuro
E
Horinouchi
Sueharu
S
D000595:Amino Acid Sequence; D015139:Blotting, Southern; D002384:Catalysis; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D019992:Databases as Topic; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008316:Malonyl Coenzyme A / Q000737:chemistry; D006899:Mixed Function Oxygenases / Q000737:chemistry*; D008956:Models, Chemical; D008957:Models, Genetic; D008969:Molecular Sequence Data; D005810:Multigene Family; D009284:Naphthols / Q000737:chemistry; D016366:Open Reading Frames; D010084:Oxidation-Reduction; D010957:Plasmids / Q000378:metabolism; D048630:Polyketide Synthases / Q000737:chemistry*; D011809:Quinones / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D013302:Streptomyces / Q000201:enzymology*; D048170:Streptomyces lividans / Q000378:metabolism; D013696:Temperature; D013997:Time Factors
C121288:1,3,6,8-tetrahydroxynaphthalene; D009284:Naphthols; D011809:Quinones; D011994:Recombinant Proteins; D008316:Malonyl Coenzyme A; D048630:Polyketide Synthases; D006899:Mixed Function Oxygenases