Mechanism of action of cerulenin on fatty acid synthetase. Effect of cerulenin on iodoacetamide-induced malonyl-CoA decarboxylase activity.
Cerulenin, an antibiotic with the structure of (2R)(3S)-2,3-epoxy-4-oxo-7,10-dodecadienoylamide, irreversibly inactivates yeast fatty acid synthetase. Of all catalytic activities of the synthetase, only the condensation reaction is inhibited by cerulenin. At 0 degrees C and pH 6.5, the second-order rate constant of k = 88 M-1 . S-1 was obtained for the inactivation by cerulenin. This value was about 90-times greater than the rate constant for the inactivation of the enzyme by iodoacetamide. The enzyme was protected against the action of cerulenin by prior treatment with acetyl-CoA but not malonyl-CoA. Treatment of the enzyme with iodoacetamide, while impairing the synthetase activity, induced malonyl-CoA decarboxylase activity [Kresze, G.-B., Steber, L., Oesterhelt, D., and Lynen, F. (1977) Eur. J. Biochem. 79, 191-199]. Cerulenin had no effect on the malonyl-CoA decarboxylase activity of the iodoacetamide-treated enzyme. N-Ethylmaleimide, in contrast, inhibited the iodoacetamide-induced malonyl-CoA decarboxylase activity. When the enzyme was preincubated with cerulenin, malonyl-CoA decarboxylase activity could not be detected even after treatment of the enzyme with iodoacetamide. These results indicated that the reaction of cerulenin with the peripheral SH-groups of the synthetase is responsible for the inactivation.
D000935:Antifungal Agents / Q000494:pharmacology*; D002262:Carboxy-Lyases / Q000378:metabolism*; D002569:Cerulenin / Q000494:pharmacology*; D005033:Ethylmaleimide / Q000494:pharmacology; D064429:Fatty Acid Synthases / Q000378:metabolism*; D007460:Iodoacetamide / Q000494:pharmacology*; D007461:Iodoacetates / Q000494:pharmacology*; D007700:Kinetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology
D000935:Antifungal Agents; D007461:Iodoacetates; D002569:Cerulenin; D064429:Fatty Acid Synthases; D002262:Carboxy-Lyases; C021532:malonyl-CoA decarboxylase; D005033:Ethylmaleimide; D007460:Iodoacetamide