title: dffA gene from Aspergillus oryzae encodes L-ornithine N5-oxygenase and is indispensable for deferriferrichrysin biosynthesis.
abstract: We identified and analyzed the dffA gene from Aspergillus oryzae which encodes L-ornithine N5-oxygenase involved in the biosynthesis of deferriferrichrysin, a type of siderophore which is a low-molecular-weight iron chelating compound. From among more than 20,000 clones in an A. oryzae EST (expressed sequence tag) library, we found only one clone encoding a protein that exhibited homology to theUstilago maydis sid1 protein (Sid1) and Pseudomonas aeruginosa pvdA protein (PvdA), both known as the only examples of L-ornithine N5-oxygenase. The complete gene sequence shows that the dffA gene includes a 1575-bp open reading frame (ORF), one 66-bp intorn, which is a typical intorn length inA. oryzae, and encodes 502 amino acids with putative FAD-binding, NADP-binding, and 'FATGY' motifs, which are conserved inN-hydroxylating enzymes. As well as that of the U. maydis sid1 gene,dffA gene expression was induced under iron-limited conditions, and the promoter region has several GATA-type transcription regulator binding motifs. When the dffA gene was expressed under the control of the a-amylase promoter in A. oryzae, transformants revealed inducible high L-ornithine N5-oxygenase activities. In addition, a dffA gene disruptant showed no deferriferrichrysin production even under iron-limited conditions. These results clearly suggest that the dffA gene is indispensable for deferriferrichrysin biosynthesis in A. oryzae.
authors.affiliation: National Research Institute of Brewing, 3-7-1 Kagamiyama, Higashi-Hiroshima 739-0046, Japan. yamada@nrib.go.jp
authors.forename: Osamu
authors.initials: O
authors.lastname: Yamada
authors.forename: Suthamas
authors.initials: S
authors.lastname: Na Nan
authors.forename: Takeshi
authors.initials: T
authors.lastname: Akao
authors.forename: Mihoko
authors.initials: M
authors.lastname: Tominaga
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Watanabe
authors.forename: Toshitsugu
authors.initials: T
authors.lastname: Satoh
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Enei
authors.forename: Osamu
authors.initials: O
authors.lastname: Akita