title: Evidence for involvement of two naphthol reductases in the first reduction step of melanin biosynthesis pathway of Colletotrichum lagenarium.
abstract: Colletotrichum lagenarium is a plant pathogenic fungus, and produces melanin that is an essential factor for appressorial penetration into host tissues. The melanin biosynthesis pathway of C. lagenarium starts with pentaketide synthesis catalyzed by polyketide synthase Pks1p. We previously confirmed that the direct product of Pks1p is 1,3,6,8-tetrahydroxynaphthalene. Thus, melanin biosynthesis in this fungus requires the reduction of 1,3,6,8-tetrahydroxynaphthalene to scytalone. We made a double mutant 9141-144 from the thr1 mutant 9141 that lacks the ability to metabolize 1,3,8-trihydroxynaphthalene. The double mutant 9141-144 could metabolize neither 1,3,6,8-tetrahydroxynaphthalene nor 1,3,8-trihydroxynaphthalene. However melanin production by the double mutant was restored by THR1, indicating that Thr1p can metabolize both compounds in vivo. These results demonstrate that two enzymes, Thr1p and a deduced 1,3,6,8-tetrahydroxynaphthalene-specific reductase, are involved in the first reduction step of the melanin biosynthesis pathway of C. lagenarium.
authors.affiliation: Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto Prefectural University, Kyoto 606-8522, Japan.
authors.forename: Gento
authors.initials: G
authors.lastname: Tsuji
authors.forename: Tomomi
authors.initials: T
authors.lastname: Sugahara
authors.forename: Isáo
authors.initials: I
authors.lastname: Fujii
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Mori
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ebizuka
authors.forename: Tomonori
authors.initials: T
authors.lastname: Shiraishi
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kubo
mesh_terms: D020231:Colletotrichum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D005656:Fungal Proteins; D015966:Gene Expression Regulation, Fungal; D008543:Melanins / Q000096:biosynthesis*; D016296:Mutagenesis; D009154:Mutation; D009284:Naphthols / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors
chemical_list: C121288:1,3,6,8-tetrahydroxynaphthalene; D005656:Fungal Proteins; D008543:Melanins; D009284:Naphthols; C012547:scytolone; C012601:vermelone; D010088:Oxidoreductases; C086024:tetrahydroxynaphthalene reductase; D044925:Oxidoreductases Acting on CH-CH Group Donors