title: Degradation of ornithine decarboxylase by the 26S proteasome.
abstract: Ornithine decarboxylase (ODC) is a key enzyme in polyamine biosynthesis. Turnover of ODC is extremely rapid and highly regulated, and is accelerated when polyamine levels increase. Polyamine-stimulated ODC degradation is mediated by association with antizyme (AZ), an ODC inhibitory protein induced by polyamines. ODC, in association with AZ, is degraded by the 26S proteasome in an ATP-dependent, but ubiquitin-independent, manner. The 26S proteasome irreversibly inactivates ODC prior to its degradation. The inactivation, possibly due to unfolding, is coupled to sequestration of ODC within the 26S proteasome. This process requires AZ and ATP, but not proteolytic activity of the 26S proteasome. The carboxyl-terminal region of ODC presumably exposed by interaction with AZ plays a critical role for being trapped by the 26S proteasome. Thus, the degradation pathway of ODC proceeds as a sequence of multiple distinct processes, including recognition, sequestration, unfolding, translocation, and ultimate degradation mediated by the 26S proteasome.
authors.affiliation: Department of Biochemistry 2, Jikei University School of Medicine, 3-25-8, Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Murakami
authors.forename: S
authors.initials: S
authors.lastname: Matsufuji
authors.forename: S
authors.initials: S
authors.lastname: Hayashi
authors.forename: N
authors.initials: N
authors.lastname: Tanahashi
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000378:metabolism; D008956:Models, Chemical; D009955:Ornithine Decarboxylase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D011506:Proteins; C031017:ornithine decarboxylase antizyme; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D009955:Ornithine Decarboxylase