Abstract
Pseudomonas syringae pv. phaseolicola, the causative agent of halo blight of French bean ( Phaseolus vulgaris L.), produces phaseolotoxin (PT), which functions as a chlorosis-inducing extracellular phytotoxin by inhibiting ornithine carbamoyltransferase (OCT). We previously demonstrated that PT also inhibits ornithine decarboxylase (ODC), a key enzyme in polyamine biosynthesis, in preparations of bean leaves. In this study, the ODC enzyme was isolated from PT-producing bacterial cultures to study enzyme characteristics and to assess the effect of PT on ODC activity. The enzyme was purified using a four-step procedure comprised of ammonium sulfate precipitation, gel filtration chromatography, ion-exchange chromatography and adsorption to hydroxylapatite. ODC was optimally active at pH 7.3 and showed hyperbolic kinetics with a K m of 0.19±0.04 mM for ornithine. PT inhibited the ODC enzyme with a K i of 16±0.05 μM. In addition, the specific suicide inhibitor DFMO also inhibited ODC with a K i of 26±0.2 μM.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
