NS1
Domain
In the N-terminus, the endonuclease region is involved in binding to the origin of replication on the viral DNA as well as to the overlapping viral promoter p6. In the middle, there are the ATPase and helicase activities. The C-terminus probably contains a transactivation domain.
Function
Multifunctional protein essential for viral DNA replication, which cooperatively interacts with the viral DNA origin of replication and transactivates several promoters including the viral p6 promoter. Binds the origin of replication and performs an endonucleolytic nick within a conserved sequence in the viral genome, thereby initiating the rolling circle replication (RCR). Participates in the transcriptional regulation the viral p6 promoter that regulates all viral transcripts and the cellular CDN1A or IL6 promoters. Transactivates several host promoters some of which induce the S cell cycle phase for the production of host replicative proteins. Up-regulates the expression of host E2F4 and E2F5 and interacts with both these factors thereby inhibiting the host cell cycle G2/M transition. This arrest promotes apoptosis for viral release.
Sequence Similarities
Belongs to the parvoviruses initiator protein NS1 family.
Cellular localization
- Host nucleus
Alternative names
Initiator protein NS1, NS1, NCVP1, Non-capsid protein NS-1, Non-structural protein 1, Non-structural protein NS1