Collisions with duplex DNA close Rep's 2B domain and trigger its return to the starting point.

HA/MACMILLAN

Some helicases continually bang their heads against the wall, if a new report from Sua Myong, Taekjip Ha (University of Illinois, Urbana-Champaign, IL), and colleagues is any indication. The Rep helicase, the group finds, repeatedly motors along a track of DNA, hits an obstacle, and returns to square one.

Not all helicases can unwind DNA, but they can all motor along it. While studying how Rep motors in a 5′ direction on single-stranded (ss) DNA, Ha's group noticed that a duplex DNA obstacle did not knock Rep off its template. Their FRET analysis instead suggested that the helicase returned to its original binding site and tried again.

Unlike the 5′ motoring, the return step was almost instantaneous. “At first it seemed like Rep was doing some sort of...

The Rockefeller University Press
2005
The Rockefeller University Press
2005
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