Chromosome arm length, and a species-specific determinant, define chromosome arm width

• Published in: Cell reports (Cambridge) Vol. 41; no. 10; p. 111753
• Main Authors: Kakui, Yasutaka, Barrington, Christopher, Kusano, Yoshiharu, Thadani, Rahul, Fallesen, Todd, Hirota, Toru, Uhlmann, Frank
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 06-12-2022
• Subjects: chromatin interactions; chromosomes; Chromosomes - genetics; condensin; H. sapiens; Hi-C; Humans; mitosis; S. cerevisiae; S. pombe; superresolution microscopy; condensin; chromatin interactions; CP: Cell biology; Hi-C; S. cerevisiae; chromosomes; H. sapiens; S. pombe; superresolution microscopy; mitosis
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2022.111753

Mitotic chromosomes in different organisms adopt various dimensions. What defines these dimensions is scarcely understood. Here, we compare mitotic chromosomes in budding and fission yeasts harboring similarly sized genomes distributed among 16 or 3 chromosomes, respectively. Hi-C analyses and superresolution microscopy reveal that budding yeast chromosomes are characterized by shorter-ranging mitotic chromatin contacts and are thinner compared with the thicker fission yeast chromosomes that contain longer-ranging mitotic contacts. These distinctions persist even after budding yeast chromosomes are fused to form three fission-yeast-length entities, revealing a species-specific organizing principle. Species-specific widths correlate with the known binding site intervals of the chromosomal condensin complex. Unexpectedly, within each species, we find that longer chromosome arms are always thicker and harbor longer-ranging contacts, a trend that we also observe with human chromosomes. Arm length as a chromosome width determinant informs mitotic chromosome formation models.
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•Chromosomes in fission yeast are thicker than in budding yeast and thinner than in humans•Chromosome widths correlate with the span of condensin-mediated chromatin contacts•In each organism, longer chromosome arms are always thicker•Longer, thicker arms inform mitotic chromosome architecture models
The factors defining chromosome shape remain an unresolved enigma. Here, Kakui et al. compare chromosome dimensions between yeasts and humans. They find that chromosomes are characterized by species-specific widths but also that within each species, longer chromosome arms are always wider. These observations challenge current models of mitotic chromosome formation.