The Enzymology of Virus-infected Bacteria: X. A BIOCHEMICAL-GENETIC STUDY OF THE DEOXYNUCLEOTIDE KINASE INDUCED BY WILD TYPE AND AMBER MUTANTS OF PHAGE T4

Abstract

Abstract A deoxynucleotide kinase induced in Escherichia coli infected with T4 bacteriophage, purified 400-fold with respect to the crude extract, catalyzes the phosphorylation of deoxythymidylate, deoxyguanylate, and 5-hydroxymethyldeoxycytidylate to the corresponding diphosphates. All three activities are inactivated at the same rate by heat and also by 8 m urea, and the three activities fractionate similarly during the purification scheme. This constitutes biochemical evidence that the three activities are catalyzed by a single enzyme. The following genetic evidence supports this view. Amber mutants of T4, defective in gene 1, do not induce any one of the three activities in the nonpermissive host, E. coli B. Spontaneous revertants of these mutants regain all three of the activities simultaneously. The enzyme induced by one of the mutants in the permissive host, E. coli CR 63, has an altered heat stability when compared to the enzyme induced by wild type T4 infecting the same host. These results indicate that a single structural gene in the bacteriophage is responsible for the synthesis of a single protein catalyzing all three activities.