Mode of Action of the Toxin from Pseudomonas phaseolicola

Abstract

A chlorosis-inducing toxin of Pseudomonas phaseolicola was examined for inhibition of ornithine carbamoyltransferease prepared from acetone powder of bean (Phaseolus vulgaris L.) plants. The

The Occurrence and Nature of Ornithine Carbamoyltransferase in Senescing Apple Leaf Tissue

“…The apple leaf enzyme seems to have binding constants very similar to those reported for the enzyme in other systems (9,14). At both pH optima, the enzyme(s) is better able to bind C-P than ORN.…”

“…At both pH optima, the enzyme(s) is better able to bind C-P than ORN. In this respect, this enzyme is similar to the one found in bacterial systems (9), but differs from the one found in the bean plant (14). The pH 8.6 enzyme has slightly higher affinities for ORN and C-P than does the pH 7.8 enzyme.…”

“…(5,7). Presumably, the ornithine synthesized by OCTase is immediately used for the synthesis of arginine (5,6 (9,10), although the enzyme from Staphylococcus aureus has a reported pH optimum of 7.3 (14).…”

“…This reaction is catalyzed by the enzyme ornithine carbamoyltransferase (EC 2. 1 .3 .3), which has been studied in bacterial (9,18), animal (10), and plant (14) …”

Biosynthesis of homoarginine and ornithine as precursors of the phytoeffector phaseolotoxin by the amidinotransfer from arginine to lysine catalyzed by an amidinotransferase in Pseudomonas syringae pv. phaseolicola

“…It produces phaseolotoxin, a tripeptide consisting of homoarginine, alanine and ornithine which is substituted in its b-aminogroup, om-P(0) (NHJ-NH-S0,H. Furthermore it produces this substituted ornithine (PNSOrn) 1977, PATIL et al 1970, TAM and PATIL 1972. Searching for the molecular basis of the resistance of P. phaseolicola against the selfproduced toxin we found a second OCT, which is insensitive to the toxin (JAHN el at.…”