A pathway for mitotic chromosome formation

TLDR

Cell biologists have long studied how cells condense DNA into rod‑shaped chromosomes during mitosis. The study mapped the minute‑by‑minute conformational transition from interphase chromatin to mitotic chromosomes across the cell cycle. Mitotic chromosomes adopt a spiral‑staircase architecture with chromatin loops radiating from a central helical scaffold, where condensin II drives helical winding and condensin I refines loop organization within each turn. Gibcus et al., Science, this issue, p.

Abstract

Tracking mitotic chromosome formation How cells pack DNA into fully compact, rod-shaped chromosomes during mitosis has fascinated cell biologists for more than a century. Gibcus et al. delineated the conformational transition trajectory from interphase chromatin to mitotic chromosomes minute by minute during the cell cycle. The mitotic chromosome is organized in a spiral staircase architecture in which chromatin loops emanate radially from a centrally located helical scaffold. The molecular machines condensin I and II play distinct roles in these processes: Condensin II is essential for helical winding, whereas condensin I modulates the organization within each helical turn. Science , this issue p. eaao6135