Melanin biosynthesis in the fungus Curvularia lunata (teleomorph: Cochliobolus lunatus).
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.
Lanisnik Rizner
Tea
T
Institute of Biochemistry, Medical Faculty, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia. Tea.Lanisnik-Rizner@mf.uni-lj.si
Wheeler
Michael H
MH
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
D005656:Fungal Proteins; D008543:Melanins; D013844:Thiazoles; D010088:Oxidoreductases; C086024:tetrahydroxynaphthalene reductase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C041191:tricyclazole