Simulations of global condensin depletion. (A) “Control” simulation with wild-type conditions, as in Fig. 1, SAC configuration. (B) Model setup (top) and simulation snapshot (bottom) for condensin I knockout (K-O)/depletion. We assume that the looping activity of condensin II (which remains after the knockout) leads to longer loops (gray arcs) and that the bridging activity (green beads) is smaller so there are fewer bridges. The fiber becomes wider and shorter. (C) Model setup (top) and snapshot (bottom) for simulations of condensin II knockout/depletion. We assume that the looping activity of condensin I (which remains after the knockout) leads to shorter loops, and that the bridging activity is larger so there are more bridges. (D) Quantitative analysis of width (left) and local stiffness (right) for the SACs in A–C. The local stiffness is computed by averaging the cosine of the θ angle between successive triplets of beads in the coarse-grained backbone (inset). The error bar is estimated by computing the mean over 10 independent simulation runs.