Spatio-temporal chromosomal arrangements by late-replicating heterochromatin

Centromere clustering orchestrates the three-dimensional genome organization and, in turn, impacts genome stability. In this study, we report the principles governing the chromosome-scale architectural changes associated with centromere clustering and declustering in Cryptococcus neoformans, an opportunistic human fungal pathogen. We demonstrate that centromeres and telomeres in C. neoformans are scattered around the nuclear periphery during interphaseG1, resembling metazoans rather than model budding yeasts. Hi-C data of the synchronised cells reveal centromere and telomere-associated heterochromatic regions are organized as separate compartments at the nuclear periphery, distinct from the euchromatic regions, that eventually shape the global organization of interphaseG1 chromosomes. Polymer modeling of the Hi-C data at interphase and anaphase stages strongly supports a global reorganization of chromosomes from the non-Rabl to the Rabl-like chromosomal arrangement. Most strikingly, while centromeres are clustered and replicate early in most yeasts, our sort-seq studies provide evidence that C. neoformans centromeres replicate late during the S-phase. In summary, we uncover yet unknown principles governing the chromosome-scale architecture that link centromere DNA replication timing, spatial centromere positioning, functional compartmentalization of chromosomes, and dynamic changes in the global three-dimensional genome architecture in a species that shared a common ancestor with metazoans more than a billion years ago. Overall design: Hi-C of synchronized Cryptococcus neoformans cells at G1, metaphase and anaphase stages of cell cycle.