Inhibition of 3-hydroxy-3-methylglutaryl coenzyme A synthase by antibiotic 1233A and other beta-lactones.

3-Hydroxy-3-methylglutaryl CoA synthase was shown to be inhibited in a time-dependent, irreversible manner by compounds containing the substituted beta-lactone functionality found in the natural product 1233A. The rate of inactivation (kinact) was found to approach the rate of catalysis (kcat). The inactivation was irreversible over several hours. A related compound lacking the hydroxymethyl substituent on the beta-lactone ring is a reversible inhibitor and is competitive with respect to acetylCoA. The results are consistent with beta-lactone ring opening by the active site Cys to form an enzyme bound thioester.