Human cytomegalovirus DNA polymerase catalytic subunit (UL54) (UL54)

Human cytomegalovirus (HCMV) DNA polymerase is a critical enzyme responsible for the replication of the viral genome during the lytic phase of infection (UniProt: P06473). It is a heterodimeric complex consisting of a catalytic subunit, encoded by the UL54 gene, and a processivity factor, encoded by the UL44 gene (PubMed: PMID 12831023). The UL54 subunit possesses both 5'-3' DNA polymerase activity and 3'-5' exonuclease proofreading activity, ensuring high-fidelity replication of the large double-stranded DNA genome (UniProt: P06473). In clinical settings, HCMV is a major cause of morbidity and mortality in immunocompromised individuals, such as transplant recipients and those with HIV/AIDS, and is a leading cause of congenital birth defects (NIH: CMV clinical overview). This enzyme serves as the primary target for most currently approved anti-CMV therapies, including ganciclovir, foscarnet, and cidofovir (StatPearls: Ganciclovir). These drugs typically act as nucleoside or nucleotide analogs that, once phosphorylated, compete with natural substrates to inhibit DNA synthesis or cause chain termination (PubMed: PMID 12831023). Foscarnet, a pyrophosphate analog, directly inhibits the enzyme by blocking the pyrophosphate binding site (StatPearls: Foscarnet). Resistance to these therapies often arises through specific mutations within the UL54 gene, which can reduce the enzyme's affinity for the drug or alter its catalytic efficiency (PubMed: PMID 12831023).

Other names

UL54HCMV DNA polymeraseDNA-directed DNA polymeraseCytomegalovirus DNA polymerasePol

Competitive inhibition of deoxyribonucleoside triphosphate (dNTP) incorporation and DNA chain termination; or direct inhibition of the pyrophosphate binding site.