  A repair protein like RecG moves the stalled replication fork in the
direction from the zipped to the unzipped state of DNA. It is proposed here
that a softening of the zipped-unzipped interface at the fork results in the
front propagating towards the unzipped side. In this scenario, an ordinary
helicase destabilizes the zipped state locally near the interface and the fork
propagates towards the zipped side. The softening of the interface can be
produced by the aromatic interaction, predicted from crystal structure, between
RecG and the nascent broken base pairs at the Y-fork. A numerical analysis of
the model also reveals the possibility of a stop and go type motion.
