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Mutations affecting uridine monophosphate pyrophosphorylase or the argR gene in Escherichia coli - Effects on carbamoyl phosphate and pyrimidine biosynthesis and on uracil uptake

par Pierard, André ;Glansdorff, Nicolas ;Yashphe, Jacob
Référence Molecular & general genetics : MGG, 118, 3, page (235-245)
Publication Publié, 1972-09

Article révisé par les pairs

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Résumé :

In the course of experiments directed towards the isolation of mutants of Escherichia coli K12 with altered regulation of the synthesis of carbamoylphosphate synthetase, two types of mutations were found to affect the cumulative repression of this enzyme by arginine and uracil. Alteraction of the arginine pathway regulatory gene, argR, was shown to reduce the repressibility of the enzyme by both end products while mutations affecting uridine monophosphate pyrophosphorylase (upp) besides affecting uracil uptake preclude enzyme repression by uracil or cytosine in the biosynthesis of carbamoylphosphate and the pyrimidines. The upp mutations were located on the chromosome near the gua operon. Mutations previously designated as uraP are shown to belong to this class. The relation that could exist between the loss of uridine monophosphate pyrophosphorylase and the impairment of uracil uptake is discussed. A new method for isolating argR mutants in arginine-less strains is described. © 1972 Springer-Verlag.