This research is designed to further elucidate the molecular mechanisms underlying the translational control of transcription termination in Escherichia coli K12 in general and to determine the genetic and biochemical regulatory mechanisms of isoleucine-valine biosynthesis specifically. In addition, fundamental knowledge about the utilization of individual tRNAs in translation and the interactions of translation machinery with RNA polymerase and termination factors will be gained. The work will employ biochemical, genetic, and physiological methodologies of molecular biology emphasizing recombinant DNA technology.