Translational regulation of deoxycytidylate hydroxymethylase and deoxynucleotide kinase synthesis in T4-infected Escherichia coli

Abstract

Almost immediately after infection of Escherichia coli with bacteriophage T4, enzymes necessary for bacteriophage DNA replication are synthesized. Synthesis of these “early” enzymes proceeds for a short time after infection and then stops while general protein synthesis continues. In the present investigation, regulation of cessation of synthesis of two early enzymes, deoxycytidylate hydroxymethylase (HMase) and deoxynucleotide kinase, was studied in T4-infected E. coli B207, a mutant of E. coli B in which the rate of protein synthesis can be regulated by the concentration of K + in the medium. In medium containing 1 m M K +, protein is synthesized at 50% the normal rate. Using this system, it was possible to show that significant amounts of functional HMase and deoxynucleotide kinase messenger RNAs were present in infected cells after synthesis of these enzymes stopped, indicating that under these conditions cessation of early enzyme synthesis is regulated at the translational level.