title: Ornithine Transcarbamylase ArgK Plays a Dual role for the Self-defense of Phaseolotoxin Producing Pseudomonas syringae pv. phaseolicola.
abstract: Pseudomonas syringae is a phytopathogenic bacterium widely spread on terrestrial plants. Sulfodiaminophosphinyl tripeptide Phaseolotoxins (PHTs), produced by P. syringae pv. phaseolicola and P. syringae pv. actinidiae, represent a kind of antimetabolic phytotoxins. PHTs inhibit host cell Ornithine transcarbamylase (OTCase) activity and induce Arginine auxotrophic phenotype. The biosynthesis of PHT is temperature dependent, being optically produced at around 18 °C, while blocked above 28 °C. PHT resistant OTCase ArgK acts as a functional replacement of housekeeping OTCase ArgF, which is the acting target of PHT, to confer PHT producers with self-resistance. It was postulated that argK might be regulated directly by a PHT biosynthetic precursor and indirectly by temperature with an unknown manner. Neither transcriptional regulator nor thermal regulation related protein encoding gene was detected from PHT biosynthetic gene cluster. The tripeptide, Cit-Ala-hArg, was identified to be a by-product of PHT biosynthetic pathway in this report. Formation of Cit-Ala-hArg was catalyzed by ArgK with tripeptide Orn-Ala-hArg and carbamyl phosphate as substrates. It showed that ArgK not only provided alternative Arginine source as reported previously, but also controlled the production of PHTs by converting PHT biosynthetic precursors to nontoxic Cit-Ala-hArg reservoir for producers' self-defense.
authors.affiliation: Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China.
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.affiliation: Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China.
authors.forename: Pin
authors.initials: P
authors.lastname: Li
authors.affiliation: Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China.
authors.forename: Zixin
authors.initials: Z
authors.lastname: Deng
authors.affiliation: Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China.
authors.forename: Changming
authors.initials: C
authors.lastname: Zhao
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D002221:Carbamyl Phosphate / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D005810:Multigene Family; D009952:Ornithine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D009954:Ornithine Carbamoyltransferase / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D044224:Pseudomonas syringae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D002221:Carbamyl Phosphate; C021234:phaseolotoxin; D009952:Ornithine; D009954:Ornithine Carbamoyltransferase