title: Lactose metabolism involving phospho-beta-galactosidase in Klebsiella.
abstract: Klebsiella strain RE1755A is a Lac- Gal- mutant which has lost both of its lac operons, but possesses a gene specifying beta-galactosidase III, an enzyme which hydrolyzes o-nitrophenyl-beta-D-galactopyranoside but does not hydrolyze lactose. Selective pressure was applied to isolate mutants able to utilize lactose. The lactose-utilizing mutants obtained were shown to possess an unaltered beta-galactosidase III. Lactose utilization was shown to result from a pleiotropic mutation which also (i) permits galactose utilization and (ii) prevents induction of beta-galactosidase III synthesis by lactose. Evidence is presented suggesting that a phospho-beta-galactosidase enzyme is involved in lactose metabolism.
mesh_terms: D005695:Galactosephosphates / Q000378:metabolism; D005696:Galactosidases / Q000378:metabolism*; D006868:Hydrolysis; D007709:Klebsiella / Q000235:genetics / Q000378:metabolism*; D007763:Lac Operon; D007785:Lactose / Q000378:metabolism*; D009154:Mutation; D009598:Nitrophenylgalactosides / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D005695:Galactosephosphates; D009598:Nitrophenylgalactosides; D005696:Galactosidases; D001616:beta-Galactosidase; D007785:Lactose