1. Model for the involvement of Rep helicases as genome packaging motors.
Model for the involvement of Rep helicases as genome packaging motors. Most helicases bind to ssDNA adjacent to duplex regions and then proceed to unwind the two strands, moving along the bound single strand, under the consumption of ATP. The AAV packaging complex represents an immobilized helicase complex, composed of large and small Rep proteins, on the capsid surface. Both ss and ds genomes are able to bind to the packaging complex via interaction with the large Rep proteins, which bind sequence specifically to both ends and covalently to the 5′ end. The genome is then translocated through the packaging complex and into the capsid either (A) as a single‐stranded molecule using the initial ‘scanning’ function before the first duplexed base pairs are encountered or (B) by unwinding a ds dimer or multimer genome on the capsid surface at the same time. (C) Simultaneous replication (arrow) of a ds monomer genome being packaged would result in premature strand displacement. Large Rep molecules at 5′ ends are covalently bound.
Jason A. King et al. EMBO J. 2001;20:
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