HSV-2 ICP8

ICP8, the herpes simplex virus single-strand DNA-binding protein, is one of seven proteins encoded in the viral genome of HSV-1 that is required for HSV-1 DNA replication. It is able to anneal to single-stranded DNA (ssDNA) as well as melt small fragments of dsDNA; its role is to destabilize duplex DNA during initiation of replication. It differs from helicases because it is ATP-and Mg2+-independent. In cells infected with HSV-1, the DNA in those cells become colocalized with ICP8. ICP8 is required in late gene transcription, and has found to be associated with cellular RNA polymerase II holoenzyme.

Full Name

Herpes Simplex Virus 2 Infected Cell Protein 8

Function

Single-stranded DNA-binding protein required for DNA replication.

Plays several crucial roles in viral infection. Participates in the opening of the viral DNA origin to initiate replication by interacting with the origin-binding protein. May disrupt loops, hairpins and other secondary structures present on ssDNA to reduce and eliminate pausing of viral DNA polymerase at specific sites during elongation. Promotes viral DNA recombination by performing strand-transfer, characterized by the ability to transfer a DNA strand from a linear duplex to a complementary single-stranded DNA circle. Can also catalyze the renaturation of complementary single strands. Additionally, reorganizes the host cell nucleus, leading to the formation of prereplicative sites and replication compartments. This process is driven by the protein which can form double-helical filaments in the absence of DNA.

Biological Process

Bidirectional double-stranded viral DNA replication Source: UniProtKB-UniRule
DNA replication Source: UniProtKB-UniRule

Cellular Location

Host nucleus. In the absence of DNA replication, found in the nuclear framework-associated structures (prereplicative sites). As viral DNA replication proceeds, it migrates to globular intranuclear structures (replication compartments).