Herpes simplex virus type 1 DNA polymerase catalytic subunit (UL30) (UL30)

The Herpes simplex virus type 1 (HSV-1) DNA polymerase catalytic subunit, encoded by the UL30 gene, is an essential enzyme for the replication of the viral genome during the lytic cycle [1, 3]. It functions as a DNA-directed DNA polymerase that synthesizes both the leading and lagging strands of the viral DNA [1]. The enzyme possesses intrinsic 5'-3' polymerase activity and 3'-5' exonuclease activity, which provides a critical proofreading function to ensure high-fidelity replication [1, 4]. To achieve high processivity, UL30 interacts with the processivity factor UL42, forming a stable complex on the DNA template [4]. This enzyme is the primary target for most clinical anti-herpetic drugs, including nucleoside analogs like acyclovir and valacyclovir [2]. These drugs are converted into active triphosphate forms that compete with natural nucleotides for incorporation into the viral DNA, leading to chain termination [2, 4]. Non-nucleoside inhibitors, such as foscarnet, also target this subunit by binding to the pyrophosphate exit site, thereby blocking nucleotide incorporation [2]. Mutations within the UL30 gene are a major mechanism of clinical resistance to these antiviral therapies, particularly in immunocompromised individuals [1, 2].

Other names

UL30DNA polymerase catalytic subunitHSV-1 DNA polymeraseDPOL_HHV11Pol

Nucleoside analogs (e.g., acyclovir) are phosphorylated by viral thymidine kinase and host kinases to triphosphate forms that compete with natural dNTPs for incorporation into viral DNA by UL30, causing chain termination [2, 4]. Pyrophosphate analogs (e.g., foscarnet) bind directly to the pyrophosphate binding site of the polymerase, preventing the cleavage of pyrophosphate from deoxynucleoside triphosphates and halting DNA chain elongation [2].