title: Mutations affecting gluconate catabolism in Escherichia coli. Genetic mapping of the locus for the thermosensitive gluconokinase.
abstract: An Escherichia coli strain unable to use gluconate was isolated by spontaneous curing of lambda cI857 s7 xis6 b515 b519, lambda cI857 s7 delta(A-att) dargI valS lysogens. Two lesions, linked to asd and pyrB markers, respectively, were necessary to produce this phenotype. The asd-linked mutation gnt-17, of regulatory type, seems to affect the expression of the major system of gluconate utilization (min 75) as well as that of 6-phosphogluconate dehydratase (gene edd, min 41), the first enzyme of the Entner-Doudoroff pathway. A closely linked suppressor of gnt-17 causes constitutivity of these activities; this suppressor resembles gntR, which is also in the asd region. Hence, it is possible that gnt-17 is a super-repressing allele of gntR, rather than a positive controlling element. Lesion gnt-17 alone does not prevent the utilization of gluconate; for this, the mutation gnt-18 at 96.9 min is also necessary. This mutation abolishes the thermosensitive gluconokinase activity and thus eliminates the subsidiary ability to catabolize gluconate. Accordingly, gnt-18 seems to be allelic with gntV, the locus postulated as being in the pyrB region specifying the thermosensitive gluconokinase.
mesh_terms: D002874:Chromosome Mapping; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D005942:Gluconates / Q000378:metabolism*; D009154:Mutation; D010770:Phosphotransferases / Q000235:genetics*; D017853:Phosphotransferases (Alcohol Group Acceptor); D014161:Transduction, Genetic
chemical_list: D005942:Gluconates; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C020578:gluconokinase