Extended Data Fig. 10: Three different models of condensin-mediated DNA loop extrusion.
From: The condensin holocomplex cycles dynamically between open and collapsed states
a, Tethered inchworm model. Here, the hinge domain anchors the DNA. The two heads are tethered by Brn1 (green), which also binds Ycg1 and Ycs4, the HEAT subunits that bind DNA. In a cyclic fashion, associated with ATP hydrolysis, these two DNA-binding domains bind and unbind from DNA (‘walk along the DNA’) to pull in target DNA. b, DNA pumping model. Ycg1 (orange) anchors DNA while the hinge domain binds to another spot along the DNA. After ATP hydrolysis, the dissociation of dimerized head domains induces a conformational change of O shape to I shape of the SMC arms. Zippering of the SMC arms pushes the hinge-bound DNA region towards the head region. After ATP binding to the head domains, the hinge domain binds to new target DNA region, and the cycle is repeated for further DNA loop extrusion. c, Scrunching model. Ycg1 (orange) anchors DNA, and the hinge domain binds to a different spot along the DNA. Through conformational changes between O shape and B shape, the hinge transfers its bound DNA to the head domain, whereupon the hinge finds a new DNA target site for further DNA loop extrusion.
