Abstract
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-adenosylmethionine decarboxylase gene (spe2) in S. pombe. The null mutant of spe2 was devoid of spermidine and spermine, accumulated putrescine, and contained a high level of ODC. Addition of spermidine to the culture medium resulted in rapid decrease in the ODC activity caused by the acceleration of ODC degradation, which was dependent on de novo protein synthesis. A fraction of ODC forming an inactive complex concomitantly increased. The accelerated ODC degradation was prevented either by knockout of antizyme gene or by selective inhibitors of proteasome. Thus, unlike budding yeast, mammalian type antizyme-mediated ODC degradation by proteasome is operating in S. pombe.
Highlights
The mechanism of the regulatory degradation of ornithine decarboxylase (ODC) by polyamines was studied in fission yeast, Schizosaccharomyces pombe
Decarboxylated S-adenosylmethionine serves as the aminopropyl donor, which is produced by S-adenosylmethionine decarboxylase (AdoMetDC, EC 4.1.1.50)
ODC is negatively regulated in response to the increase in cellular polyamines mainly through a unique mechanism mediated by a protein termed antizyme [4, 5]
Summary
The mechanism of the regulatory degradation of ornithine decarboxylase (ODC) by polyamines was studied in fission yeast, Schizosaccharomyces pombe. Addition of spermidine to the culture medium resulted in rapid decrease in the ODC activity caused by the acceleration of ODC degradation, which was dependent on de novo protein synthesis. ODC is negatively regulated in response to the increase in cellular polyamines mainly through a unique mechanism mediated by a protein termed antizyme [4, 5].
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