DNA and RNA polymerase active sites (Pol active sites)

DNA and RNA polymerase active sites are the highly conserved catalytic regions within polymerase enzymes responsible for the synthesis of nucleic acids. These sites facilitate the formation of phosphodiester bonds between nucleotides, typically employing a two-metal-ion mechanism involving magnesium or manganese ions to coordinate the incoming nucleoside triphosphate and the 3-prime hydroxyl group of the primer strand (Source: Steitz, Nature, 1998). Because these enzymes are indispensable for the replication of viruses, bacteria, and rapidly dividing cancer cells, their active sites serve as critical targets for antiviral, antibacterial, and antineoplastic therapies. Therapeutic agents such as nucleoside analogs mimic natural nucleotides to inhibit synthesis through chain termination or competitive inhibition (Source: NIH, PubChem). However, the structural conservation between pathogen polymerases and human host polymerases, particularly the mitochondrial DNA polymerase gamma, poses a significant challenge for drug selectivity and can lead to clinical toxicities (Source: Lewis et al., Nature Reviews Drug Discovery, 2003). This target entry is considered broad as it encompasses a wide variety of distinct enzymes across different species and functional classes.

Other names

Polymerase catalytic domainNucleotide binding siteNucleotidyltransferase active centerPalm domain catalytic siteTwo-metal-ion catalytic center

Drugs targeting these sites primarily act as nucleoside or nucleotide analogs that compete with natural substrates for binding. Once incorporated into the growing strand, they often function as obligate or non-obligate chain terminators, preventing further elongation of the DNA or RNA polymer (Source: PubMed, PMID: 32457171). Other inhibitors, such as non-nucleoside reverse transcriptase inhibitors (NNRTIs) or rifamycins, bind to allosteric sites near the active center to induce conformational changes that block catalytic activity (Source: Nature Reviews Drug Discovery, 2003).