Summary
A new type of mutant of mutant of Escherichia coli that synthesises thymidine phosphorylase constitutively has been isolated and characterised. The mutation leading to constitutivity is located to the left of the gene specifying deoxyriboaldolase. The mutation is cis dominant in its effect on thymidine phosphorylase activity and therefore believed to be a mutation of the operator-constitutive type. The specific activity of purine nucleoside phosphorylase is not affected by the mutation indicating that the gene specifying this enzyme is located in a different operon from that containing the genes specifying thymidine phosphorylase and deoxyriboaldolase.
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Ahmad, S. I., Pritchard, R. H.: A map of four genes specifying enzymes involved in catabolism of nucleosides and deoxynucleosides in Escherichia coli. Molec. gen. Genet. 104, 351 (1969).
Ahmad, S. I., Pritchard, R. H.: A regulatory mutant affecting the synthesis of enzymes involved in the catabolism of nucleosides in Escherichia coli. Molec. gen. Genet. 111, 77 (1971).
Barth, P. T., Beacham, I. R., Ahmad, S. I., Pritchard R. H.: The inducer of the deoxynucleoside phosphorylase and deoxyriboaldolase in Escherichia coli. Biochim. biophys. Acta (Amst.) 161, 554 (1968).
Beacham, I. R., Barth, P. T., Pritchard, R. H.: Constitutivity of thymidine phosphorylase in deoxyriboaldolase negative strains: dependence on thymine requirement and concentration. Biochim. biophys. Acta (Amst.) 166, 589 (1968).
Bonney, R. J., Weinfeld, H.: Regulation of thymidine metabolism in Escherichia coli K-12: studies on the inducer and the coordinate-ness of induction of the enzymes. J. Bact. 106, 812 (1971).
Burton, K.: A study of the conditions and mechanism, of the diphenylamine reaction for the colorimetric estimation of deoxyribonucleic acid. Biochem J. 62, 315 (1956).
Hayes, W.: The mechanism of genetic recombination in Escherichia coli. Cold Spr. Harb. Symp. quant. Biol. 18, 75 (1953).
Low, B.: Formation of merodiploids in matings with a class of rec - recipient strains of Escherichia coli K12. Proc. nat. Acad. Sci. (Wash.) 60, 160 (1968).
Munch-Petersen, A.: On the catabolism of deoxynucleosides in cells and cell extracts of Escherichia coli. Europ. J Biochem. 6, 432 (1968).
Munch-Petersen, A.: Deoxyribonucleoside catabolism and thymine incorporation in mutants of Escherichia coli lacking deoxyriboaldolase. Europ. J. Biochem. 15, 191 (1970).
Robertson B. C., Jargiello, P., Blank, J., Hoffee, P. A.: Genetic regulation of ribonucleoside and deoxyribonucleoside catabolism in Salmonella typhimurium. J. Bact. 102, 628 (1970).
Taylor, A. L., Trotter, C. D.: Linkage map of Escherichia coli strain K-12. Bact. Rev. 36, 504 (1972).
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Ahmad, S.I., Pritchard, R.H. An operator constitutive mutant affecting the synthesis of two enzymes involved in the catabolism of nucleosides in Escherichia coli . Molec. Gen. Genet. 124, 321–328 (1973). https://doi.org/10.1007/BF00267661
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DOI: https://doi.org/10.1007/BF00267661