Deoxyribonucleic acid polymerases of Euglena gracilis. Primer-template utilization of and enzyme activities associated with the two deoxyribonucleic acid polymerases of high molecular weight

Abstract

The two high-molecular-weight DNA polymerases from Euglena gracilis, pol A (mol. wt. 190 000) and pol B (mol. wt. 240 000), were differentiated on the basis of associated enzymic activities and primer-template utilization. Neither enzyme had endodeoxyribonuclease activity, but pol B, like pol B of yeast and the corresponding enzyme from Tetrahymena pyriformis, exhibited at least one other nuclease activity directed against denatured DNA and the RNA of an RNA-DNA hybrid. These nuclease functions preferred an alkaline pH and Mg2+. Pol B also exhibited nucleoside diphosphokinase activity. Both enzymes were active with 'activated' DNA and poly[d(A-T)] as primer-templates and were sensitive, especially pol B, to inhibition by excess of native or heat-denatured DNA. Pol B also utilized oligo[d(T)] and poly(A) templates under certain conditions, whereas pol A exhibited only slight activity with poly[d(A)]. (U)6 was not used as a primer by either enzyme.

The deoxyribonucleic acid polymerases from the diatom Cylindrotheca fusiformis. Subcellular distribution, exonuclease activity and heterogeneity of the enzymes

“…Both the presence of a DNAase associated with the diatom pol D, and its properties, agree with characterizations reported for other protists: presumably a 3': 5'-exonuclease, the DNAase in yeasts (Helfman, 1973), Euglena (McLennan & Keir, 1975c), Tetrahymena (Crerar & Pearlman, 1974), U. maydis ), as well as in the diatom, has a requirement for Mg2+, a pH optimum higher than that for polymerase activity, and a preference for single-stranded DNA (except in U. maydis where its preference is for native DNA).…”

The deoxyribonucleic acid polymerases from the diatom Cylindrotheca fusiformis. Partial purification and characterization of four distinct activities

“…The diatom pol D shares some unusual properties in common with the pol B activity of Euglena (McLennan & Keir, 1975b) and yeast (Wintersberger, E., 1974). These enzymes have some activity on the synthetic template primers, poly[d(A)] oligo[d(T)10] and poly(A).oligo[d(T)IO].…”

Some Aspects of Eukaryotic DNA Replication

“…Two large molecular weight enzymes, designated A and B, have been isolated fr om Euglena gracilis (70,71). Polymerase A appears to be predominantly nuclear, and the B enzyme predominantly cytoplasmic (72).…”