Panta rhei: Chromatin remodeling dynamics.

Chromatin remodeling governs how eukaryotic genomes are accessed and interpreted by dynamically modulating nucleosome architecture. Adenosine triphosphate (ATP)-dependent remodeling complexes are highly conserved molecular machines built around Snf2-family ATPases that use the energy of ATP hydrolysis to slide, evict, or restructure nucleosomes, thereby shaping transcription, replication, and DNA repair. Their importance is such that their malfunctioning is linked to different diseases, including cancer. Recent discoveries reveal that chromatin remodelers are far more dynamic than previously appreciated: they undergo continual motion, rapid exchange, and transient nucleosome engagement, underscoring a highly fluid regulatory landscape. To capture this emerging view, we invoke Heraclitus' aphorism panta rhei (ancient Greek: πάντα ῥεῖ, 'everything flows, moves'), which aptly reflects the intrinsic dynamism of remodeling processes. Advances in single-molecule imaging and high-resolution structural approaches now illuminate how remodelers search the genome, transition between functional states, and remodel nucleosomes in real time. This review synthesizes recent developments, with emphasis on SWItch/Sucrose Non-Fermentable (SWI/SNF) complexes and comparative insights across remodeler families, highlighting how integrating structural, biochemical, and biophysical perspectives is reshaping current models of chromatin regulation.