Inhibition of bacterial luminescence by cerulenin

Bacterial luminescence is very sensitive to cerulenin, a fungal inhibitor of fatty acid (FA) synthesis. Cerulenin does not inhibit luciferase itself, but rather the synthesis of its aldehyde substrate by FA reductase. The acyl-CoA reductase (58 kDa) component of the Photobacterium phosphoreum FA reductase complex was inhibited by cerulenin in vitro. Similarly, acylation of the corresponding Vibrio harveyi 57 kDa protein with (/sup 3/H)myristic acid was preferentially decreased, while cerulenin had no effect on the activities of luciferase or the acyltransferase (32 kDa) responsible for FA supply to luminescence. Light emission of wild type V. harveyi was less sensitive to cerulenin at 10 ..mu..g/ml (5-fold decrease at 1h) than that of the FA-stimulatable dark mutant M17 (100-fold inhibition), which lacks the 32 kDa acyltransferase. The V. harveyi reductase subunit was also labeled by (/sup 3/H)tetrahydrocerulenin in vivo in M17 but not wild type cells; this labeling could be prevented by preincubating M17 cells with cerulenin or FA. These results suggest that (a) cerulenin specifically and covalently inhibits the reductase component of aldehyde synthesis, and (b) this enzyme is partially protected from inhibition in vivo in the wild type cell.