Submitted to: International Geminivirus Symposium
Publication Type: Abstract Only
Publication Acceptance Date: November 1, 2003
Publication Date: February 15, 2004
Citation: Cheung, A.K. 2004. A novel rolling-circle DNA replication mechanism for porcine circovirus. 2nd International ssDNA Comparative Virology Workshop. Paper No. 17/2 S2-4. Technical Abstract: Rolling-circle replication (RCR) mechanism is utilized by both prokaryotes and eukaryotes to synthesize their DNAs. The current "stem-loop" RCR model for circular DNAs suggests a cruciform structure is induced at the origin of DNA replication (Ori) by a replicator protein binding to its cognate recognition site. Here, I propose a new "melting-pot" RCR model for porcine circovirus DNA replication and demonstrate that an Ori flanking palindrome is not essential for initiation; but one is generated inevitably, at termination. The replicator protein-complex provides a melting-pot environment that destabilizes the Ori sequence and initiates DNA polymerization, but there is no formation of a cruciform structure. Instead, all four strands of the inverted repeats exist in a "melted" configuration capable of serving as templates for leading-strand DNA synthesis. Inherent in this model is a "terminal repeat correction" mechanism that can restore mutilated inverted repeat sequences at the Ori of circular DNAs or at the termini of circularized linear DNAs provided that an intact copy is available as template.