Transcription-coupled recruitment of SMC complexes in yeast.

Despite their distinct biological functions, structural maintenance of chromosomes (SMC) complexes, including cohesin, condensin, and SMC5/6, preferentially accumulate at transcriptionally active loci, with recent studies revealing that SMC5/6 also shares the loop extrusion mechanism previously considered a hallmark of cohesin and condensin. Using yeast as a model system, this review discusses how RNA polymerases I, II, and III, together with their associated transcriptional machinery, contribute to the recruitment of SMC complexes to specific genomic sites. We examined the reciprocal interplay between transcription and SMC complexes, highlighting how transcription activity and SMC-driven chromatin organization influence each other. We further explore how SMC complexes recognize and respond to transcription-induced topological changes, such as positive supercoiling and R-loops. We propose that SMC complexes and transcription machineries form a dynamic regulatory network that coordinates the three-dimensional genome architecture with gene expression. Defining how each SMC complex is distinctly coordinated with RNA polymerase machineries and their associated factors, and how these complexes sense and resolve transcription-associated DNA topologies, represents an important frontier for future research.