Three domains in the simian virus 40 core origin orchestrate the binding, melting, and DNA helicase activities of T antigen

This is the authors' abstract. We don't add key points for this paper.

The simian virus 40 (SV40) core origin of replication consists of three functional domains. The sequence 5'-CACTACTTCTGGAATAG-3' with an imperfect inverted repeat (underlined), a palindrome with four 5'-GAGGC-3' pentanucleotide repeats, and a 17-base-pair A + T-rich segment. We have been able to assign primary functions to each domain. Remarkably, SV40 large T antigen melted the inverted repeat domain in the complete absence of other origin sequences. Presumably, this protein-DNA interaction initiates a replication bubble that leads to daughter strand DNA synthesis. The pentanucleotide domain alone docked and arranged T antigen at the origin. The A + T-rich domain had no independent function, but, in the presence of the other two domains, allowed bound T antigen to extend the replication bubble. Thus, three domains of the origin coordinate the binding, melting, and DNA helicase activities of T antigen in an ordered sequence of events to initiate DNA replication.