Factors affecting the formation of alkaline phosphatase isozymes in Escherichia coli K-12.

Physiological and genetic factors affecting the formation of isozymes of alkaline phosphatase in Escherichia coli K-12 were studied. Our results are compatible with the hypothesis proposed by Schlesinger and his co-workers (Schlesinger et al., 1975) that the multiple forms of the enzyme are produced by converting a newly synthesized one (the least negatively charged one) into less negatively charged forms. Neither energy source nor de novo synthesis of the enzyme was necessary for the conversion. It is also confirmed that the conversion is effectively inhibited by externally added arginine (Piggott et al., 1972) but only partially by canavanine (arginine analog) or casamino acids. We isolated a mutant strain which did not form isozyme(s), if any, under the condition in which the wild type strain formed isozymes. The mutation(s) was proved to be mapped in the locus (or loci) other than alkaline phosphatase structure gene in the E. coli genetic map. We tentatively proposed to designate this the iap gene(s), an abbreviation for isozyme of alkaline phosphatase, which plays a role in isozyme formation.