title: ValC, a new type of C7-Cyclitol kinase involved in the biosynthesis of the antifungal agent validamycin A.
abstract: The gene valC, which encodes an enzyme homologous to the 2-epi-5-epi-valiolone kinase (AcbM) of the acarbose biosynthetic pathway, was identified in the validamycin A biosynthetic gene cluster. Inactivation of valC resulted in mutants that lack the ability to produce validamycin A. Complementation experiments with a replicating plasmid harboring full-length valC restored the production of validamycin A, thus suggesting a critical function of valC in validamycin biosynthesis. In vitro characterization of ValC revealed a new type of C7-cyclitol kinase, which phosphorylates valienone and validone--but not 2-epi-5-epi-valiolone, 5-epi-valiolone, or glucose--to afford their 7-phosphate derivatives. The results provide new insights into the activity of this enzyme and also confirm the existence of two different pathways leading to the same end-product: the valienamine moiety common to acarbose and validamycin A.
authors.affiliation: Department of Pharmaceutical Sciences, Oregon State University, Corvallis, OR 97331-3507, USA.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Minagawa
authors.forename: Yirong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Takuya
authors.initials: T
authors.lastname: Ito
authors.forename: Linquan
authors.initials: L
authors.lastname: Bai
authors.forename: Zixin
authors.initials: Z
authors.lastname: Deng
authors.forename: Taifo
authors.initials: T
authors.lastname: Mahmud
mesh_terms: D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000096:biosynthesis* / Q000737:chemistry; D002240:Carbohydrate Sequence; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D003001:Cloning, Molecular; D016213:Cyclins / Q000378:metabolism*; D053138:Cyclohexenes / Q000737:chemistry; D006595:Hexosamines / Q000096:biosynthesis / Q000737:chemistry; D007294:Inositol / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000737:chemistry; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010770:Phosphotransferases / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013056:Spectrophotometry, Ultraviolet; D013302:Streptomyces / Q000201:enzymology / Q000235:genetics
chemical_list: D000935:Antifungal Agents; D016213:Cyclins; D053138:Cyclohexenes; D006595:Hexosamines; D011994:Recombinant Proteins; C030790:validamycin A; C030791:valienamine; D007294:Inositol; D010770:Phosphotransferases