The aliphatic acylamide amidohydrolase of Mycobacterium smegmatis: its inducible nature and relation to acyl-transfer to hydroxylamine.

Abstract

SUMMARY Mycobacterium smegmatis nctc 8159 grew well in a minimal medium with succinate or acetamide as sole carbon source. Washed bacteria or cell-free extracts hydrolyzed 15 monocarboxylic amides, but not 4 related N-substituted amides. Formamide was the best substrate, followed by n-butyramide. Extracts of bacteria grown on acetamide hydrolyzed formamide about 60 times and butyramide about 20 times as rapidly as bacteria grown on succinate. Other short-chain fatty acylamides were also more rapidly hydrolyzed, but benzamidase activity was not similarly induced by growth on acetamide. Extracts of bacteria grown on succinate transferred acyl groups from propionamide, butyramide and nicotinamide to hydroxylamine, to form hydroxamates. Transferase activity, unlike aliphatic amidase activity in extracts was purified twofold and freed from transferase activity. Formamidase and butyramidase activities were not separated, and were similarly affected by heat and dithio-bis-nitrobenzoic acid. The amidase was induced by growth on acetate and on butyramide, but not on propionate, butyrate or benzamide, all of which were good growth-substrates. N-methylacetamide and N-acetyl-acetamide were non-substrate inducers of amidase for bacteria growing on succinate.