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The “ORC” twists, pinches, and dances around DNA

The Origin Recognition Complex (ORC) is a key piece of cellular machinery, fundamental to life, yet so far mysterious. This video shows the shape of the ORC in 3D as published in eLife. One segment shows the complex twirling with and without straddling a piece of DNA. Another shows how the ORC twists and pinches. A third segment shows how ORC2 swings around the other subunits to cover the cavity where DNA binds. In the fourth segment, ORC1 and ORC4 form an energy processing structure; the researchers think that energy is required to move around the subunits. The scientists speculate that at least some of these movements are critical for the ORC to recruit replication enzymes or for the ORC to be ejected from the origin site once the replication machinery arrives. The fifth segment shows how part of the complex can cover the DNA binding site, almost as though that subunit is trying to protect it (“O2 WHD auto-inhibited state”). The proteins were visualized using cryo-electron microscopy (cryo-EM). The models and video clips were made using Cryosparc 2 and UCSF ChimeraX software. Images/videos: Matt Jaremko/CSHL Joshua-Tor lab.

Read the related story: Replicating a genome starts with a twist, a pinch, and a bit of a dance