Identification of cis-acting sites for condensin loading onto budding yeast chromosomes.

Eukaryotic chromosomes reach their stable rod-shaped appearance in mitosis in a reaction dependent on the evolutionarily conserved condensin complex. Little is known about how and where condensin associates with chromosomes. Here, we analyze condensin binding to budding yeast chromosomes using high-resolution oligonucleotide tiling arrays. Condensin-binding sites coincide with those of the loading factor Scc2/4 of the related cohesin complex. The sites map to tRNA and other genes bound by the RNA polymerase III transcription factor TFIIIC, and ribosomal protein and SNR genes. An ectopic B-box element, recognized by TFIIIC, constitutes a minimal condensin-binding site, and TFIIIC and the Scc2/4 complex promote functional condensin association with chromosomes. A similar pattern of condensin binding is conserved along fission yeast chromosomes. This reveals that TFIIIC-binding sites, including tRNA genes, constitute a hitherto unknown chromosomal feature with important implications for chromosome architecture during both interphase and mitosis.