ENZYMATIC SYNTHESIS OF DEOXYRIBONUCLEIC ACID. INFLUENCE OF BACTERIOPHAGE T2 ON THE SYNTHETIC PATHWAY IN HOST CELLS

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Abstract
Three enzymes which are undetectable in extracts of uninfected or in T5-infected cells are first detectable about 4 minutes after Escherichia coli is infected with phage T2 (1) an enzyme which catalyzes the phosphorylation by ATP of hydroxymethyldeoxycytidine-5-phosphate (dHMC-5-P), the product of the dHMC-5-P kinase action shown to be the triphosphate; (2) an enzyme, the inhibitor of dC-5-P kinase, which splits deoxycytidine triphosphate (dCTP) by removal of the terminal pyrophosphate group; and (3) an enzyme which transfers glucose from uridine diphosphate glucose (UDPG) to DNA containing hydroxymethyl-cytosine (HMC). These enzymes can account for the presence of the triphosphate of hydroxymethyldeoxycytidine for the synthesis of T2 DNA and the absence of deoxycytidy late, as well as the presence of glucose on a fixed fraction of the hydroxymethylcytosine residues in DNA. DNA synthesis is increased 12-fold in extracts prepared 19 minutes after infection with T2 when dHMC-TP is substituted for dCTP. After T2 infections the kinase levels for thymine and guanine deoxynucleotide phosphorylating enzymes (dT-5-P and dG-5-P) were increased approximately 20 and 45 times, respectively, whereas that for adenine deoxynucleotide phosphorylating enzyme (dA-5-P) remained essentially unchanged. Only traces of cytosine deoxynucleotide phosphorylating enzyme (dC-5-P kinase) were detected. Infection with phage T5 containing cytosine rather than HMC showed increased kinase activities for the 4 deoxynucleotides which are present in its DNA.