Rate-limiting pyrophosphate release by hepatitis C virus polymerase NS5B improves fidelity [Enzymology]

In this study, we used transient-state kinetics to examine the mechanistic basis for polymerase fidelity. We observe a wide range of efficiency for incorporation of various mismatched base pairs and have uncovered a mechanism in which the rate constant for pyrophosphate release is slowed for certain misincorporation events. This results in an increase in fidelity against these specific misincorporations. Furthermore, we discover that some mismatches are highly unfavorable and cannot be observed under the conditions used here. The calculated fidelity of NS5B ranges between 10−4–10−9 for different mismatches.
Source: Journal of Biological Chemistry - Category: Chemistry Authors: Tags: Enzymology Source Type: research