@article{mbs:/content/journal/micro/10.1099/00221287-132-11-3209, author = "Istúriz, Tomás and Palmero, Eduardo and Vitelli-Flores, Juana", title = "Mutations Affecting Gluconate Catabolism in Escherichia coli. Genetic Mapping of the Locus for the Thermosensitive Gluconokinase", journal= "Microbiology", year = "1986", volume = "132", number = "11", pages = "3209-3219", doi = "https://doi.org/10.1099/00221287-132-11-3209", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-132-11-3209", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "SUMMARY: An Escherichia coli strain unable to use gluconate was isolated by spontaneous curing of λc1857 s7 xis6 b515 b519, λc1857 s7 Δ(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.", }