Glucosylation of Deoxyribonucleic Acid II. wGLUCOSYL TRANSFERASES FROM T2- AND TG-INFECTED ESCHERICHIA COLI*t

The deoxyribonucleic acid of the bacterial viruses, T2, T4, and T6, is unique in containing the pyrimidine base, 5-hydroxymethylcytosine, in place of cytosine (2). Attached to a fraction of the 5-hydroxymethylcytosine residues are glucosyl or diglucosyl units in amounts and linkages characteristic for each of the phages. 5-Hydroxymethylcytosine residues with ar-monoglucosyl substituents occur in the deoxyribonucleic acids of T2, T4, and T6, whereas the @ derivative is found only in T4 deoxyribonucleic acid; T2 and T6 contain diglucosyl units also (3). During the course of infection of Escherichia coli by these phages, a group of enzymes is formed whose action appears to account for the type of glucosyl deoxyribonucleic acid being synthesized. T2-, T4-, and TB-infected cells contain enzymes which form ol-glucosyl units, whereas T4-infected cells have a second enzyme which synthesizes the /3 derivative; an enzyme yielding diglucosyl units was also demonstrated in TG-infected cells (I). The uniqueness of the glucosylation reactions as examples of enzymatic addition of substituents to polymerized deoxyribonucleic acid has prompted further study of two of these enzymes, the T2-and TG-5-hydroxymethylcytosine-cY-glucosyl transferases. The same general reaction is catalyzed by both enzymes.