title: Melanin biosynthesis in the fungus Curvularia lunata (teleomorph: Cochliobolus lunatus).
abstract: Curvularia lunata (teleomorph: Cochliobolus lunatus) is a known plant and human pathogen. Tricyclazole, a specific inhibitor of pentaketide melanin biosynthesis, blocked the biosynthesis of melanin in Curvularia lunata and caused the accumulation of the melanin metabolites flaviolin and 2-hydroxyjuglone. This showed that melanin in Curvularia lunata is produced by a pentaketide pathway from 1,8-dihydroxynaphthalene. The 1,3,8-trihydroxynaphthalene reductase (3HNR) gene, associated with the melanin pathway of Curvularia lunata, was identified and characterized. An alignment of 3HNR sequences enabled the design of primers covering conserved regions. A PCR-amplified fragment of Curvularia lunata genomic DNA was used for screening the cDNA library. Three independent cDNA clones revealed an 801-bp open reading frame encoding a 267 amino acid protein. The protein was expressed in Escherichia coli and purified to homogeneity. The predicted amino acid sequence of the 28.6-kDa protein demonstrated homology to other fungal 3HNR and other members of the short-chain dehydrogenase super family. Northern analyses revealed that 3HNR from Curvularia lunata is expressed synchronously with melanization after 3 days of Curvularia lunata growth in malt extract medium. No 3HNR reductase gene expression nor melanization was observed when Curvularia lunata was grown in yeast nitrogen base medium.
authors.affiliation: Institute of Biochemistry, Medical Faculty, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia. Tea.Lanisnik-Rizner@mf.uni-lj.si
authors.forename: Tea
authors.initials: T
authors.lastname: Lanisnik Rizner
authors.forename: Michael H
authors.initials: MH
authors.lastname: Wheeler
mesh_terms: D001203:Ascomycota / Q000145:classification / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D001483:Base Sequence; D003001:Cloning, Molecular; D005656:Fungal Proteins; D015966:Gene Expression Regulation, Fungal; D023281:Genomics; D008543:Melanins / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010088:Oxidoreductases / Q000235:genetics; D044925:Oxidoreductases Acting on CH-CH Group Donors; D010802:Phylogeny; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013844:Thiazoles / Q000494:pharmacology
chemical_list: D005656:Fungal Proteins; D008543:Melanins; D013844:Thiazoles; D010088:Oxidoreductases; C086024:tetrahydroxynaphthalene reductase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C041191:tricyclazole