EFFECT OF SYRINGOMYCIN-E AND SYRINGOPEPTINS ON ISOLATED PLANT-MITOCHONDRIA

Syringomycin E. syringopeptin 22-A and syringopeptin 25-A, the main ph ytotoxins isolated from cultures of several strains of Pseudomonas syr ingae pv. 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 syringo mycin E. They were also more active in increasing the respiration of s uccinate and NADH and the hydrolysis of ATP in isolated maize and pea mitochondria, and in decreasing the membrane potential of those mitoch ondria. These results explain the apparent contrast between the findin gs obtained some years ago with toxin preparations which had been cons idered homogeneous, but in fact contained multiple forms of syringomyc ins and syringopeptins, and those obtained using pure syringomycin E. (C) 1996 Academic Press Limited