Figure 1.

Catalytic activities of PabPolB mediated by Mg²⁺ or Ca²⁺. (A) Primer-template used for primer extension and 3′-exonuclease primer degradation experiments, in panels B–D, respectively. It consists of a Cy5-labeled 17-mer primer annealed to a DNA template of 87-nt in length. (B) Extension of the 17/87 primer-template by PabPolB at the indicated Mg²⁺ or Ca²⁺ concentrations. The numbers under the gel lanes represent the total percentage of full-length products and extension. Reference oligodeoxynucleotides of 17 and 87 bases are indicated on the right. (C) Extension of the 17/87 primed-template (25 nM) by PabPolB (75 nM) at fixed Mg²⁺ or Ca²⁺ concentrations (5 mM) and 200 μM dNTPs in a time course experiment at 55°C. The numbers under the gel lanes represent the total percentage of full-length products. Reference oligodeoxynucleotides of 17 and 87 bases are indicated on the right. (D) Proofreading exonucleolysis of 17/87 primer-template at the indicated Mg²⁺ or Ca²⁺ concentrations. The numbers under the gel lanes represent the percentage of degraded primers. Reference oligodeoxynucleotides of 17 and 8 bases are indicated on the right.