Nucleic Acids Research, 1978, Vol. 5, No. 10 3959-3974
© 1978
Articles |
Ribonucleotidyl transferase in preparations of partially purified DNA polymerase
of the sea urchin
Department of Biological Chemistry, University of Illinois Medical Center Chicago, IL 60612, USA
Received June 19, 1978.
Three ribonucleotidyl transferase types have been described in the sea urchin: riboadenylate transferase, the DNA dependent RNA polymerases, and a DNA polymerase associated ribonucleotidyl transferase (Biochemistry 15:31063113, 1976). In the present work this latter ribonucleotidyl transferase was found to purify with DNA polymerase
through phosphocellulose, DEAE Sephadex and DNA cellulose and to cosediment t 6.5 S. This ribonucleotidyl transferase was active with Mn+2 , but not Mg+2 on calf thymus DNA and poly(dC). Other synthetic templates elicited DNA polymerase
but no ribonucleotidyl transferase activity. From alkaline hydrolysates of the poly(dC) directed GTP polymerization, we found Goh and Gp in a ratio of 1:16 indicating an average chain length of 17 residues after a 20 min reaction. Co-polymerization of GTP (5 µM) and dGTP (10 µM) yielded a non-random distribution of the ribonucleotide in the deoxyribonucleotide. The properties of this urchin ribonucleotidyl transferase are unlike any previously described eukaryotic transferase and the data is discussed with reference to the known properties of E. coli DNA polymerase I and the primase.