Chromosomal Location of a Gene Involved in Potassium Ion Uptake in Escherichia coli B.

A chromosomal lesion responsible for defective potassium ion uptake in Escherichia coli B has been mapped by use of standard interrupted-mating crosses. The mutation, kac-1, is in strain RD-2, which is deficient in K(+) intake, exchanges cell K(+) for extracellular isotope at a reduced rate, and has an abnormality of phosphorus metabolism associated with its potassium deficiency. This report places kac-1 at about 4 min clockwise from pro, close to gal. The locus of kac-1 is distinctly different from the potassium retention mutant in strain B-207, the only other potassium accumulation mutant mapped in E. coli so far. In this study, two other potassium accumulation mutations, kac-2 and kac-3, whose particular type of accumulation defects have not yet been determined, were mapped. These mutations are in the same region of the chromosome as kac-1.