Global genome organization mediated by RNA polymerase III-transcribed genes in fission yeast.

Eukaryotic genomes exist as an elaborate three-dimensional structure in the nucleus. Recent studies have shown that this higher-order organization of the chromatin fiber is coupled to various nuclear processes including transcription. In fission yeast, we demonstrated that RNA polymerase III (Pol III)-transcribed genes such as tRNA and 5S rRNA genes, dispersed throughout chromosomal arm regions, localize to centromeres in interphase. This centromeric association of Pol III genes, mediated by the condensin complex, becomes prominent during mitosis. Here, we discuss potential roles of the Pol III gene-mediated genome organization during interphase and mitosis, and hypothesize that the interphase genome structure serves as a scaffold for the efficient assembly of condensed mitotic chromosomes and that tethering of chromosomal arm regions to centromeres allows chromosomes to properly segregate along the spindle microtubules during anaphase.