REPRESSION OF THE VALINE-ISOLEUCINE PATHWAY IN SALMONELLA

Abstract

Investigations of the repression of the pathway for the synthesis of valine and isoleucine in wild-type Salmonella typhimurium show that threonine, a precursor of isoleucine is required in addition to valine, isoleucine, and leucine to repress maximally the reductoisomerase (one of the two repressible enzymes). Available evidence emphasizes the unusual complexities associated with the regulatory mechanisms of the pathway. Several features of the repression phenomenon are discussed.