Human DNA Polymerase Gamma for Testing the Effect of Drugs on Mitochondrial Function

One of the primary means for treating HIV infection is the use of antiviral nucleotide or nucleoside analogs. These analogs work by inhibiting the activity of reverse transcriptase, the enzyme responsible for preparing the HIV genome for integration into the DNA of the host cell. Although these analogs do not have an effect on the polymerases responsible for replicating the human genome, the polymerase responsible for replicating the mitochondrial genome is sensitive to these analogs. When patients are exposed to nucleotide or nucleoside analogs through long-term treatment regimens, the replication of the mitochondrial genome can be adversely affected. Since mitochondrial functionality is necessary for cell activity, the nucleotide and nucleoside analogs can cause serious and unwanted side-effects.

This invention concerns the cloning and purification of DNA polymerase gamma, the polymerase responsible for replicating the mitochondrial genome. The enzymes that have been purified include the wild-type version, a version which lacks exonuclease (proofreading) activity, and several versions with modified activity due to the mutation of the enzyme. These purified enzymes can be used to directly test the effects of new drugs that affect the activity of polymerases, such as nucleotide and nucleoside analogs.