Growth, enzyme levels, and some metabolic properties of an Escherichia coli mutant grown on L-threonine as the sole carbon source.
A mutant of Escherichia coli (designated E. coli SBD-76) that utilizes L-threonine as the sole carbon source was isolated. In contrast with levels in extracts of wild-type cells, the levels of threonine dehydrogenase in extracts of this mutant were 100-fold higher than levels of threonine aldolase or degradative threonine dehydratase. Catabolite repression of threonine dehydrogenase was manifested in wild-type, but not SBD-76, cells. For purposes of isolating enzymes, large quantities of SBD-76 cells with the elevated threonine dehydrogenase level could be grown in a fermentor in modified Fraser medium containing 1% glycerol, rather than in the 0.2% L-threonine minimal medium used to isolate the mutant. SBD-76 cells grown on L-threonine excreted glycine and aminoacetone into the medium, and extracts of the mutant strain catalyzed a quantitative conversion of L-threonine to glycine and aminoacetone.
D000096:Acetone / Q000031:analogs & derivatives / Q000378:metabolism; D000429:Alcohol Oxidoreductases / Q000378:metabolism; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005798:Genes, Bacterial; D005947:Glucose / Q000494:pharmacology; D005998:Glycine / Q000378:metabolism; D012696:Glycine Hydroxymethyltransferase / Q000378:metabolism; D009154:Mutation; D013912:Threonine / Q000378:metabolism*; D013913:Threonine Dehydratase / Q000378:metabolism
D003470:Culture Media; D000096:Acetone; D013912:Threonine; D000429:Alcohol Oxidoreductases; C023159:L-threonine 3-dehydrogenase; D012696:Glycine Hydroxymethyltransferase; D013913:Threonine Dehydratase; D005947:Glucose; D005998:Glycine; C006495:aminoacetone