title: Rhizobitoxine production in Agrobacterium tumefaciens C58 by Bradyrhizobium elkanii rtxACDEFG genes.
abstract: We examined the genetic basis and transfer for production of rhizobitoxine, an inhibitor of ethylene biosynthesis in plants, directed by the rtx genes of Bradyrhizobium elkanii. Comparison with genome sequences of Bradyrhizobium japonicum and Xanthomonas oryzae suggests that the rtx genes extend from the previously identified rtxAC genes through four additional genes rtxDEFG. Reverse transcription-PCR analysis showed that the rtxACDEFG genes are expressed as an operon. Mutational analysis indicated that rtxDEG mutants reduced rhizobitoxine biosynthesis, while the rtxA gene is essential for its synthesis. Introduction of the rtxACDEFG into Agrobacterium tumefaciens resulted in strong expression of rtxACDEFG and production of RtxA protein, but no rhizobitoxine was detectable. Addition of O-acetylhomoserine, a precursor of rhizobitoxine, to the Agrobacterium derivative, however, fostered production of rhizobitoxine in culture. The diluted culture supernatant inhibited the activities of beta-cystathionase and 1-aminocyclopropane-1-carboxylate synthase, indicating that A. tumefaciens carrying rtxACDEFG genes excreted biologically active rhizobitoxine.
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Katahira, Aoba-ku, Sendai, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sugawara
authors.forename: Ryota
authors.initials: R
authors.lastname: Haramaki
authors.forename: Satoko
authors.initials: S
authors.lastname: Nonaka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ezura
authors.forename: Shin
authors.initials: S
authors.lastname: Okazaki
authors.forename: Shima
authors.initials: S
authors.lastname: Eda
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Mitsui
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Minamisawa
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D020369:Bradyrhizobium / Q000235:genetics* / Q000378:metabolism; D006714:Homoserine / Q000031:analogs & derivatives / Q000378:metabolism; D008190:Lyases / Q000037:antagonists & inhibitors; D009154:Mutation; D009876:Operon; D030781:Organisms, Genetically Modified / Q000378:metabolism; D011412:Propanolamines / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D001426:Bacterial Proteins; D011412:Propanolamines; D006714:Homoserine; D008190:Lyases; C021773:1-aminocyclopropanecarboxylate synthase; C019965:cystathionine beta-lyase; C041618:rhizobitoxine