Essential for the replication of viral ssDNA. The closed circular ssDNA genome is first converted to a superhelical dsDNA. Rep and/or Rep' binds a specific hairpin at the genome origin of replication. Introduces an endonucleolytic nick within the conserved sequence 5'-AGTATTAC-3' in the intergenic region of the genome, thereby initiating the rolling circle replication (RCR). Following cleavage, binds covalently to the 5'-phosphate of DNA as a tyrosyl ester. The cleavage gives rise to a free 3'-OH that serves as a primer for the cellular DNA polymerase. The polymerase synthesizes the (+) strand DNA by rolling circle mechanism. After one round of replication, a Rep-catalyzed nucleotidyl transfer reaction releases a circular single-stranded virus genome, thereby terminating the replication. Displays origin-specific DNA cleavage, nucleotidyl transferase, ATPase and helicase activities. ATPase activity is probably carried by the isoform Rep (By similarity). ATP + H2O = ADP + H(+) + phosphate Divalent metal cations, possibly Mg(2+) or Mn(2+). Interacts with the capsid protein; this interaction relocates Rep into the nucleus. There are 3 rolling circle replication (RCR) motifs. RCR-2 is probably involved in metal coordination. RCR-3 is required for phosphodiester bond cleavage for initiation of RCR. Belongs to the nanoviruses/circoviruses replication-associated protein family.