Abstract 1115 Kinetic studies of the incorporation of a potent antiviral NRTI by human DNA polymerases

This is the authors' abstract. We don't add key points for this paper.

Nucleoside reverse transcriptase inhibitors (NRTIs) are one of the most commonly prescribed class of antiviral drugs used to combat human immunodeficiency virus infections, which causes AIDS. These drugs prevent virus genomic replication upon incorporation into the viral DNA and terminating further DNA synthesis. Unfortunately, these drugs can cause harmful side effects to patients. It is believed that many of these unwanted side effects are due to NRTI incorporation into host DNA through nuclear and mitochondrial DNA polymerases. It is well established in vitro and in vivo that NRTI incorporation by human DNA polymerase γ is correlated with mitochondrial toxicity. It has been shown that many NRTIs can also be incorporated by human X- and Y- family DNA polymerases, which are important in nuclear DNA repair and DNA lesion bypass, but less efficiently than natural dNTPs. Using pre-steady-state kinetic methods, we measured the substrate specificity constants of the 5'-triphosphate of an investigational NRTI incorporated by human DNA polymerases β, γ, δ, ε, λ, κ, α, η, and Rev1. For all nine enzymes investigated, the NRTI was incorporated less efficiently than dATP, due to weaker binding affinity and a slower incorporation rate. We also found that when comparing the kinetic parameters of the NRTI between the aforementioned DNA polymerases, human DNA polymerases α and γ incorporated the NRTI most efficiently while human DNA polymerases β and λ were the least efficient. Our kinetic results suggest that the NRTI incorporation by human DNA polymerases α and γ is a potential mechanism for the observed toxicity of the NRTI, while its effects on DNA polymerases that are key in nuclear DNA repair is less of a factor. This work has been financially supported by the Florida State University startup fund to Zucai Suo.