Multifunctional protein which displays endonuclease and helicase activities required for initiating and directing viral DNA replication. Also plays a role in viral packaging and transactivation of several promoters. Binds site-specifically to 2-3 approximate tandem copies within the origins of replication (Ori), unwinds this hairpin region and nicks one DNA strand thereby initiating the rolling circle replication (RCR). Becomes covalently attached to the 5' end of the nick and provides a 3'OH for priming DNA synthesis. The helicase activity unwinds DNA in a 3'-5' direction on the longer strand. Participates in the transcriptional regulation of several promoters. ATP + H2O = ADP + H(+) + phosphate The endonuclease active site can probably bind other divalent cations. Homooligomer; when bound to DNA. In the N-terminus, the endonuclease region is involved in binding to the origin of replication. In the middle, there are the ATPase and helicase activities. The C-terminus probably contains a transactivation domain. Belongs to the parvoviruses initiator protein NS1 family.