Effect of syringomycin-E and syringopeptins on isolated plant mitochondria

Abstract

Syringomycin E, syringopeptin 22-A and syringopeptin 25-A, the main phytotoxins isolated from cultures of several strains of Pseudomonas syringaepv. syringae, were separately tested for their activity on some mitochondrial functions. It was shown that syringopeptins were several-fold more active uncouplers of oxidative phosphorylation than syringomycin E. They were also more active in increasing the respiration of succinate and NADH and the hydrolysis of ATP in isolated maize and pea mitochondria, and in decreasing the membrane potential of those mitochondria. These results explain the apparent contrast between the findings obtained some years ago with toxin preparations which had been considered homogeneous, but in fact contained multiple forms of syringomycins and syringopeptins, and those obtained using pure syringomycin E.