Condensin extrudes DNA loops in steps up to hundreds of base pairs that are generated by ATP binding events.

ABSTRACT: The condensin SMC protein complex organizes chromosomal structure by extruding loops of DNA. Its ATP-dependent motor mechanism remains unclear but likely involves steps associated with large conformational changes within the ∼50 nm protein complex. Here, using high-resolution magnetic tweezers, we resolve single steps in the loop extrusion process by individual yeast condensins. The measured median step sizes range between 20-40 nm at forces of 1.0-0.2 pN, respectively, comparable with the holocomplex size. These large steps show that, strikingly, condensin typically reels in DNA in very sizeable amounts with ∼200 bp on average per single extrusion step at low force, and occasionally even much larger, exceeding 500 bp per step. Using Molecular Dynamics simulations, we demonstrate that this

SUBMITTER: Ryu JK 

PROVIDER: S-EPMC8789078 | biostudies-literature | 2022 Jan

REPOSITORIES: biostudies-literature