Mapping of purine markers inEscherichia coliK 12

Abstract

A number of mutants ofE. coliK 12, deficient in purine biosynthesis, have been isolated and the biochemical blocks have been determined. The mutations were mapped in conjugation experiments. In some cases the differences in penetration times were too small to determine the exact order of the loci by interrupted mating experiments. In these cases the recombination frequencies were determined in four factor crosses. In this way the location of eleven different purine markers has been determined. The loci are scattered over the chromosome. Only two groups of linked genes were found.

Regulation of Purine and Pyrimidine Metabolism

“…A similar collection of purine auxotrophs, with corresponding linkage groups and map positions, has been found in Escherichia coli [18]. Direct determination of corresponding enzyme deficiencies has not been made in most cases, but by phenotypic inference and map positions, a unified nomenclature of the E. coli genes has been made to correspond to that of the Salmonella data of Table I [ 19].…”

Characterization of the nadR locus in Escherichia coli

“…Precedents for positive regulation have been established in the L-arabinose (8) and the alkaline phosphatase (14) systems of E. coli as well as the sulfur metabolism pathway of Nezrrospora (reviewed in 12). In the L-arabinose system the araC+ gene has two mutant alleles; araC is recessive to araC+ and araCCis dominant to araC.…”

Mapping of the gene for cytosine deaminase on theEscherichia coli chromosome

“…2. Mutations were introduced with N-methyl-N-nitroso-N'-nitroguanidine (nitrosoguanidine) (Stouthamer, de Haan and Nijkamp, 1965). Mutants were isolated after penicillin enrichment.…”