Mechanisms of DNA Polymerases

The role of DNA polymerases in cancer development are explored and their activities in various chemotherapeutic modalities is exploited. It is found that error-prone polymerases bind dNTP substrate prior to interacting with damaged DNA, necessitating substrate addition. The number of nucleotides added to the labeled DNA after the addition of the chase provides a direct indication of polymerase processivity. The viral polymerase can partition the chain-terminated pimer from the P-site back into the N-site, favoring the binding of PP i. With polymerase such as E. coli Klenow fragment, the contribution of a conformational change step adds approximately 60-fold selectivity by providing additional time to excise mismatches before DNA dissociations. Biochemical analysis show that the increased sensitivity to a certain drug combination reflects the inability to the pol-η-deficient cells to restart stalled DNA synthesis.