Insights into the Molecular Mechanism of Polymerization and Nucleoside Reverse Transcriptase Inhibitor Incorporation...

Area of Science:

• Biochemistry
• Molecular Biology
• Virology

Background:

• Human PrimPol is a novel DNA/RNA primase-polymerase in the archaeo-eukaryotic primase (AEP) superfamily, identified as the second mitochondrial polymerase.
• Mitochondrial DNA polymerase γ (mtDNA Pol γ) interactions with nucleoside reverse transcriptase inhibitors (NRTIs) are a primary cause of NRTI-associated toxicity, a critical concern for HIV treatment.
• Understanding host polymerase interactions with nucleoside analogs is vital for preventing adverse events in patients on lifelong antiviral or anticancer therapies.

Purpose of the Study:

• To investigate the polymerization mechanism of human PrimPol with natural nucleotide and NRTI substrates.
• To assess the potential for PrimPol-mediated toxicity from nucleoside analog incorporation.
• To compare PrimPol's NRTI incorporation kinetics with that of mtDNA Pol γ.

Main Methods:

• Transient-kinetic analysis of polymerization for each nucleotide and NRTI substrate catalyzed by PrimPol.
• Characterization of PrimPol's substrate selectivity and catalytic efficiency.

Main Results:

• PrimPol exhibits distinct polymerization kinetics for nucleotide and NRTI substrates.
• Nucleotide selectivity limits chemical catalysis, with product release being the rate-limiting step.
• PrimPol incorporates four of eight FDA-approved antiviral NRTIs, with a kinetic profile differing from mtDNA Pol γ.

Conclusions:

• PrimPol's unique NRTI incorporation profile suggests a potential role in NRTI-associated toxicity.
• These findings are crucial for evaluating the safety of antiviral therapies involving NRTIs.
• Further research into PrimPol's interaction with nucleoside analogs is warranted to mitigate potential adverse effects.