Isolation of Mutants Affecting Tryptophanase Production in Escherichia coli

Abstract

Gartner, Theodore K. (University of California, Davis), and Monica Riley . Isolation of mutants affecting tryptophanase production in Escherichia coli . J. Bacteriol. 89: 313–318. 1965.—Mutants of Escherichia coli K-12 were isolated which appear to have suffered an alteration in the regulation system governing tryptophanase synthesis. A novel selection method was used to isolate tryptophanase mutants from tryptophan synthetase deletion mutants. Mutants were obtained which exhibited the following phenotypes either singly or in combination with others: constitutivity and inducibility at 13 C (wild type is not inducible at 13 C), constitutivity and hyperinducibility at 37 C. Mutation to constitutivity at 13 C seems to require two mutational changes of the wild type. Other mutants, presumably structural gene mutations, were isolated which lack tryptophanase activity under all conditions tested.