title: Characterization of the hom-thrC-thrB cluster in aminoethoxyvinylglycine-producing Streptomyces sp. NRRL 5331.
abstract: Three genes from the aminoethoxyvinylglycine (AVG)-producing Streptomyces sp. NRRL 5331 involved in threonine biosynthesis, hom, thrB and thrC, encoding homoserine dehydrogenase (HDH), homoserine kinase (HK) and threonine synthase (TS), respectively, have been cloned and sequenced. The hom and thrC genes appear to be organized in a bicistronic operon as deduced by disruption experiments. The thrB gene, however, is transcribed as a monocistronic transcript. The encoded proteins are quite similar to the HDH, HK and TS proteins from other bacterial species. The overall organization of these three genes, in the order hom-thrC-thrB, differs from that in other bacteria and is similar to that reported in the Streptomyces coelicolor genome sequence. This is the first time in which the gene cluster for the three last steps of threonine biosynthesis has been characterized from a streptomycete. Disruption of thrC indicated that threonine is not a direct precursor for AVG biosynthesis in Streptomyces sp. NRRL 5331 and suggested that the branching point of the aspartic acid-derived biosynthetic route of this metabolite should lie earlier on the threonine biosynthetic route.
authors: Institute of Biotechnology INBIOTEC, Parque Cientı́fico de León, Avda. del Real, no 1, 24006 León, Spain1.
authors: Mónica
authors: M
authors: Fernández
authors: Institute of Biotechnology INBIOTEC, Parque Cientı́fico de León, Avda. del Real, no 1, 24006 León, Spain1.
authors: Yolanda
authors: Y
authors: Cuadrado
authors: Institute of Biotechnology INBIOTEC, Parque Cientı́fico de León, Avda. del Real, no 1, 24006 León, Spain1.
authors: Eliseo
authors: E
authors: Recio
authors: Area of Microbiology, Faculty of Biology, University of León, 24071 León, Spain2.|Institute of Biotechnology INBIOTEC, Parque Cientı́fico de León, Avda. del Real, no 1, 24006 León, Spain1.
authors: Jesús F
authors: JF
authors: Aparicio
authors: Area of Microbiology, Faculty of Biology, University of León, 24071 León, Spain2.|Institute of Biotechnology INBIOTEC, Parque Cientı́fico de León, Avda. del Real, no 1, 24006 León, Spain1.
authors: Juan F
authors: JF
authors: Martı N
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D019757:Carbon-Oxygen Lyases / Q000737:chemistry / Q000235:genetics*; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial; D023061:Gene Order; D005798:Genes, Bacterial / Q000235:genetics; D005998:Glycine / Q000031:analogs & derivatives* / Q000378:metabolism*; D006715:Homoserine Dehydrogenase / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D013302:Streptomyces / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D013912:Threonine / Q000096:biosynthesis; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D013912:Threonine; D006715:Homoserine Dehydrogenase; D017853:Phosphotransferases (Alcohol Group Acceptor); C021370:homoserine kinase; D019757:Carbon-Oxygen Lyases; C023160:threonine synthase; C088137:aminoethoxyvinylglycine; D005998:Glycine