Activation of mitochondrial ATP-dependent protease by peptides and proteins.
We examined the effect of peptides or protein on the proteolytic and ATPase activities of mitochondrial ATP-dependent LON protease purified from bovine adrenal cortex. Peptides/proteins including angiotensin I which stimulated ATPase activity without hydrolysis of any peptide bonds stimulated proteolysis of 125I-labeled substrates at low concentrations; whereas at high concentrations they competitively inhibited proteolysis, thus displaying a biphasic activity profile. All peptides and proteins thus examined stimulated degradation of 125I-labeled substrates. When an ATP analog was substituted for ATP, only inhibition; i.e., no stimulation, of proteolysis by unlabeled peptides was observed. Without activator peptides, degradation of [125I] peptides was higher in the presence of an ATP analog than that in the presence of ATP. ADP, a product of the ATPase reaction, inhibited the proteolytic activity in the absence of an activator peptide but not in its presence. From analogy to E. coli ATP-dependent protease La (LON), we suggest that the activator peptides stimulated the proteolysis by releasing enzyme-bound ADP.
Watabe
S
S
Faculty of Health Sciences, Yamaguchi University School of Medicine, Ube, Japan. shwatabe@yamaguchi-u.ac.jp
Hara
M
M
Yamamoto
M
M
Yoshida
M
M
Yamamoto
Y
Y
Takahashi
S Y
SY
D049069:ATP-Dependent Proteases; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000302:Adrenal Cortex / Q000201:enzymology*; D000803:Angiotensin I / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D004789:Enzyme Activation; D006360:Heat-Shock Proteins / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology*; D012697:Serine Endopeptidases / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013379:Substrate Specificity; D001615:beta-Endorphin / Q000494:pharmacology*
D006360:Heat-Shock Proteins; D007328:Insulin; D012710:Serum Albumin, Bovine; D001615:beta-Endorphin; D000255:Adenosine Triphosphate; D000803:Angiotensin I; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases