Primer:Template DNA duplex (P/T DNA)

The primer:template DNA duplex is a fundamental molecular structure consisting of a short oligonucleotide primer hybridized to a longer single-stranded DNA template (Alberts et al., Molecular Biology of the Cell). This complex serves as the essential substrate for DNA polymerases, which utilize the free 3'-hydroxyl group of the primer to initiate the sequential addition of deoxyribonucleotides during DNA synthesis (Kornberg & Baker, DNA Replication). In the context of pharmacology, the primer:template duplex is the primary site of action for nucleoside and nucleotide reverse transcriptase inhibitors (NRTIs) used in the treatment of HIV and Hepatitis B (NIH, HIV/AIDS Glossary). These drugs are analogs of natural nucleotides that, once phosphorylated, compete for incorporation into the growing primer strand; their incorporation leads to premature chain termination because they lack the necessary 3'-hydroxyl group for further phosphodiester bond formation (PubChem, Zidovudine). Beyond viral infections, the stability and processing of the primer:template junction are critical in human DNA repair pathways and the maintenance of genomic integrity, with implications for cancer progression and treatment (Nature Reviews Molecular Cell Biology). Therapeutic challenges associated with targeting this complex include the emergence of viral resistance mutations and off-target inhibition of human mitochondrial DNA polymerase gamma, which can lead to systemic toxicities (PubMed, Mitochondrial toxicity of NRTIs).

Other names

Primer-template junctionDNA primer-template complexP/T junctionPrimer-template DNA

Competitive inhibition and chain termination of DNA synthesis through incorporation into the primer strand