Glycerol Catabolic Enzymes and Their Regulation in Wild-type and Mutant Strains of Streptomyces coelicolor A3(2)

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Abstract
Assay procedures were developed for a soluble glycerol kinase [apparent Km (glycerol) 9 .mu.M] and a probably membrane-associated, NAD-independent L-glycerol-3-phosphate dehydrogenase [apparent Km (L-glycerol 3-phosphate) 7 mM] present in S. coelicolor A3(2). Both enzymes were cold sensitive. They were co-ordinately induced (about 35-fold) by addition of glycerol to cultures growing on arabinose as sole C source. Induction was rifampicin sensitive. The dehydrogenase was absent from glycerol-sensitive mutants and kinase and dehydrogenase were absent from glycerol non-utilizing (but glycerol-resistant) mutants, demonstrating that the 2 enzymes are part of the major pathway of glycerol catabolism in S. coelicolor. Circumstantial evidence suggested that their inducer is glycerol 3-phosphate rather than glycerol. The enzymes were subject to co-ordinate repression by various C sources, of which glucose exerted the strongest effect (a 5-fold repression). Previously described mutants resistant to 2-deoxyglucose, have a very low glucose kinase activity and were defective in glucose repression of the glycerol enzymes.