A sensitive and quantitative bioassay, based on the ability of the exotoxin of Pseudomonas glycinea to inhibit ornithine carbamoyltransferase of bean, was employed in a comparative study of the P. glycinea and P. phaseolicola toxins using high-voltage electrophoresis, thin-layer chromatography, ultrafiltration, and Sephadex-gel chromatography. The P. glycinea toxin (glytoxin) has an elution volume/void volume (Ve/V0) ratio different from that of phaseotoxin when chromatographed on Sephadex G-25. Glytoxin passes through a membrane filter with an exclusion limit of 500 daltons whereas phaseotoxin does not. High voltage electrophoresis in buffers of different pH values showed that glytoxin, like phaseotoxin, migrates as an anion but shows greater mobility than phaseotoxin. Both toxins degrade on thin layers of silica gel. Glytoxin induces chlorosis in bean and soybean leaf tissues, and like phaseotoxin, is an inhibitor of ornithine carbamoyltransferase but not of aspartate carbamoyltransferase. Glytoxin is presumably responsible for the accumulation of ornithine which was observed in soybean leaves infected with P. glycinea. Our studies show that glytoxin and phaseotoxin are similar but not identical.
Start site selection at the TATA-less carbamoyl-phosphate synthase (glutamine-hydrolyzing)/aspartate carbamoyltransferase/dihydroorotase promoter.
