Molecular and General Genetics MGG

, Volume 111, Issue 1, pp 77–83 | Cite as

A regulatory mutant affecting the synthesis of enzymes involved in the catabolism of nucleosides in Escherichia coli

  • S. I. Ahmad
  • R. H. Pritchard


A regulatory mutant which leads to constitutive synthesis of enzymes involved in catabolism of nucleosides is described. It is unlinked to the structural genes whose activity is affected. The gene concerned is designated nucR. The amount of thymine required for growth (colony formation) of thy strains is affected by the nucR mutation. The amount required by a thydrmstrain is reduced about four fold if it carries the constitutivity mutation. The amount required by a thydrm+strain is increased at least two fold. These differences in nutritional requirement provide a method for selecting constitutives from non-constitutives and vice versa.











inorganic phosphate


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Copyright information

© Springer-Verlag 1971

Authors and Affiliations

  • S. I. Ahmad
    • 1
  • R. H. Pritchard
    • 1
    • 2
  1. 1.Department of GeneticsUniversity of LeicesterLeicesterEngland
  2. 2.School of BiologyUniversity of LeicesterLeicesterEngland

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