Post-translational and transcriptional regulation of polyamine biosynthesis in Escherichia coli

Abstract

• 1.

  1. Ornithine and arginine decarboxylases (ODC and ADC) of Escherichia coli are inhibited post-translationally by antizyme and ribosomal proteins S20 and L34.

• 2.

  2. The inhibition of either enzyme is relieved when excess of the other decarboxylase is added.

• 3.

  3. Using this approach, in vitro as well as in vivo, we demonstrate that the extent of the post-translational inhibition of ODC and ADC in E. coli is at least 65 and 50%, respectively.

• 4.

  4. The inhibited enzyme levels increase even further upon exposure of cells to polyamines.

• 5.

  5. The post-translational mode of regulation can counteract a 4-fold increase of ODC protein in the cell.

• 6.

  6. The negative transcriptional regulation of ODC and ADC expression by polyamines is mediated by transcription factors and not by direct polyamine effects on the promoters of their genes.

• 7.

  7. Three proteins interacting with the ODC promoter region were found by southwestern blot analysis.