Figure 10.

The contribution of polar and steric filters towards sugar selectivity in B-family DNA polymerases. Y424 and N497 represent the steric and polar filters in PolII (E. coli), a representative member of the B-family of dPols. (A) Primer extension assays were carried out to compare the ability of PolII-WT, PolII-Y424L and PolII-Y424L+N497A to incorporate rCTPs. These assays show that the polar filter contributes substantially towards ribonucleotide exclusion in this family. (B) Further, primer extension assays showed that the mutations Y424L and Y424L+N497A did not have a significant effect on the ability of PolII to incorporate dCTPs. For both the graphs, the error bars indicate standard deviation (n = 3).