Regulatory Mutations Affecting the Gluconate System in Escherichia coli |
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| Authors: | No Zwaig, Rosa Nagel de Zwaig, Tom s Istú riz, Magda Wecksler |
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| Affiliation: | Noé Zwaig, Rosa Nagel de Zwaig, Tomás Istúriz, and Magda Wecksler |
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| Abstract: | A spontaneously arising regulatory mutant of the gluconate system in Escherichia coli was isolated. This mutant became constitutive, probably in one step, for gluconate high-affinity transport, gluconokinase, and gluconate-6-P dehydrase. The mutation involved (gntR18) is cotransducible with asd. Pseudorevertants, derived from a mutant (M2) that shows a long lag for growth on gluconate mineral medium, were also isolated and characterized. They give constitutive levels of gluconokinase and gluconate-6-P dehydrase but lack high-affinity transport function. Genetic experiments performed with one of these pseudorevertants (M4) indicate that it carries a secondary mutation in the gntR gene. The M4 phenotype is thus the result of the interaction of expression of a constitutive mutation (gntR4) with the mutation of strain M2 (gntM2). |
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