Structural highlights
Function
SMC4_YEAST Central component of the condensin complex, a complex required for conversion of interphase chromatin into mitotic-like condense chromosomes. The condensin complex probably introduces positive supercoils into relaxed DNA in the presence of type I topoisomerases and converts nicked DNA into positive knotted forms in the presence of type II topoisomerases.
Publication Abstract from PubMed
Structural maintenance of chromosomes (SMC) protein complexes structure genomes by extruding DNA loops, but the molecular mechanism that underlies their activity has remained unknown. We show that the active condensin complex entraps the bases of a DNA loop transiently in two separate chambers. Single-molecule imaging and cryo-electron microscopy suggest a putative power-stroke movement at the first chamber that feeds DNA into the SMC-kleisin ring upon adenosine triphosphate binding, whereas the second chamber holds on upstream of the same DNA double helix. Unlocking the strict separation of "motor" and "anchor" chambers turns condensin from a one-sided into a bidirectional DNA loop extruder. We conclude that the orientation of two topologically bound DNA segments during the SMC reaction cycle determines the directionality of DNA loop extrusion.
A hold-and-feed mechanism drives directional DNA loop extrusion by condensin.,Shaltiel IA, Datta S, Lecomte L, Hassler M, Kschonsak M, Bravo S, Stober C, Ormanns J, Eustermann S, Haering CH Science. 2022 Jun 3;376(6597):1087-1094. doi: 10.1126/science.abm4012. Epub 2022 , Jun 2. PMID:35653469[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Shaltiel IA, Datta S, Lecomte L, Hassler M, Kschonsak M, Bravo S, Stober C, Ormanns J, Eustermann S, Haering CH. A hold-and-feed mechanism drives directional DNA loop extrusion by condensin. Science. 2022 Jun 3;376(6597):1087-1094. PMID:35653469 doi:10.1126/science.abm4012
