Antizyme regulates the degradation of ornithine decarboxylase in fission yeast Schizosaccharomyces pombe - Study in the spe2 knockout strains

The mechanism of the regulatory degradation of ornithine decarboxylase (ODC ) by polyamines was studied in fission yeast, Schizosaccharomyces pombe. To regulate cellular spermidine experimentally, we cloned and disrupted S-ade nosylmethionine decarboxylase gene (spe2) in S. pombe. The null mutant of s pe2 was devoid of spermidine and spermine, accumulated putrescine, and cont ained a high level of ODC. Addition of spermidine to the culture medium res ulted in rapid decrease in the ODC activity caused by the acceleration of O DC degradation, which was dependent on de novo protein synthesis. A fractio n of ODC forming an inactive complex concomitantly increased. The accelerat ed ODC degradation was prevented either by knockout of antizyme gene or by selective inhibitors of proteasome. Thus, unlike budding yeast, mammalian t ype antizyme-mediated ODC degradation by proteasome is operating in S. pomb e.