Centromeric motion facilitates the mobility of interphase genomic regions in fission yeast

Abstract

Dispersed genetic elements such as retrotransposons and Pol III-transcribed genes, including tRNA and 5S rRNA, cluster and associate with centromeres in fission yeast through the condensin function. However, the dynamics of these condensin-mediated genomic associations remains unknown. We have examined the 3D motions of genomic loci including the centromere, telomere, ribosomal DNA (rDNA) repeat locus, and the loci carrying Pol III-transcribed genes or LTR retrotransposons in live cells at as short as 1.5-sec intervals. Treatment with carbendazim (CBZ), a microtubule-destabilizing agent, not only prevents centromeric motion, but also reduces the mobility of the other genomic loci during interphase. Further analyses demonstrate that condensin-mediated associations between centromeres and the genomic loci are clonal, infrequent, and transient. However, when associated, centromeres and the genomic loci migrate together in a coordinated fashion. In addition, a condensin mutation that disrupts associations between centromeres and the genomic loci results in a concomitant decrease in the mobility of the loci. Our study suggests that highly mobile centromeres pulled by microtubules in cytoplasm serve as “genome mobility elements” by facilitating physical relocations of associating genomic regions.