Abstract
The regulation of thiamine biosynthesis in E. coli has been studied. The thiamine biosynthesis is regulated by repression and derepression of the formation of enzymes involved in the thiamine synthesis from OMP and Th depending on the cellular TDP concentration, which is varied by addition of exogenous thiamine, adenine, or phenylalanine to the growth medium. This mechanism of the regulation is supported by the isolation of two kinds of thiamine regulatory mutants ; one is assumed to be an operator-constitutive strain of thiamine operon (s) and the other shows altered regulatory properties of thiamine synthesis probably due to an alteration in the promotor region of thiamine operon (s). These mutants were selected as pyrithiamineresistant strains of E.coli K12 and its derivative.
