title: Cloning and insertional inactivation of Streptomyces argillaceus genes involved in the earliest steps of biosynthesis of the sugar moieties of the antitumor polyketide mithramycin.
abstract: Two genes (mtmD and mtmE) were cloned and sequenced from the mithramycin producer Streptomyces argillaceus. Comparison with proteins in databases and enzymatic assays after expression in Escherichia coli showed that they encode a glucose-1-phosphate:TTP thymidylyl transferase and a TDP-D-glucose 4,6-dehydratase, respectively. The mtmD gene was inactivated by gene replacement, generating a nonproducing mutant that accumulates a tetracyclic compound designated premithramycinone. The identification of premithramycinone reveals new aspects of the mithramycin biosynthetic pathway and suggests that at least some glycosylations occur before breakage of the fourth ring.
authors.affiliation: Departamento de Biología Funcional, Instituto Universitario de Biotecnología de Asturias (IUBA-CSIC), Universidad de Oviedo, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Lombó
authors.forename: K
authors.initials: K
authors.lastname: Siems
authors.forename: A F
authors.initials: AF
authors.lastname: Braña
authors.forename: C
authors.initials: C
authors.lastname: Méndez
authors.forename: K
authors.initials: K
authors.lastname: Bindseil
authors.forename: J A
authors.initials: JA
authors.lastname: Salas
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial; D006836:Hydro-Lyases / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics*; D016254:Mutagenesis, Insertional; D009713:Nucleotidyltransferases / Q000235:genetics* / Q000502:physiology; D008926:Plicamycin / Q000096:biosynthesis*; D013302:Streptomyces / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism
chemical_list: D000903:Antibiotics, Antineoplastic; D001426:Bacterial Proteins; D009097:Multienzyme Complexes; D009713:Nucleotidyltransferases; C020587:glucose-1-phosphate thymidylyltransferase; D006836:Hydro-Lyases; C022771:dTDPglucose 4,6-dehydratase; D008926:Plicamycin