Increased Activity of Tryptophan Biosynthetic Enzymes in Histidine Mutants of Neurospora crassa

Abstract

Carsiotis , M. (University of Cincinnati College of Medicine, Cincinnati, Ohio), and Ann M. Lacy . Increased activity of tryptophan biosynthetic enzymes in histidine mutants of Neurospora crassa . J. Bacteriol. 89: 1472–1477. 1965.—The activities of tryptophan synthetase and indoleglycerol phosphate synthetase, the last two enzymes in the tryptophan biosynthetic pathway, are elevated twofold or more in all histidine mutants of Neurospora crassa . The elevation occurs only when the mutants are grown in a histidine-limited medium. Several possible mechanisms for this elevation were disproved experimentally. The cause of the elevated enzyme activities remains unknown.