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bioRxiv · 10.1101/237834

A quantitative map of human Condensins provides new insights into mitotic chromosome architecture

Walther, N.·Hossain, M. J.·Politi, A. Z.·Koch, B.·Kueblbeck, M.·Oedegaard-Fougner, O.·Lampe, M.·Ellenberg, J.
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Abstract

The two Condensin complexes in human cells are essential for mitotic chromosome structure. We used homozygous genome editing to fluorescently tag Condensin I and II subunits and mapped their absolute abundance, spacing and dynamic localization during mitosis by fluorescence correlation spectroscopy-calibrated live cell imaging and super-resolution microscopy. While [~]35,000 Condensin II complexes are stably bound to chromosomes throughout mitosis, [~]195,000 Condensin I complexes dynamically bind in two steps, in prometaphase and early anaphase. The two Condensins rarely co-localize at the chromatid axis, where Condensin II is centrally confined but Condensin I reaches [~]50% of the chromatid diameter from its center. Based on our comprehensive quantitative data, we propose a three-step hierarchical loop model of mitotic chromosome compaction: Condensin II initially fixes loops of a maximum size of [~]450 kb at the chromatid axis whose size is then reduced by Condensin I binding to [~]90 kb in prometaphase and [~]70 kb in anaphase, achieving maximum chromosome compaction upon sister chromatid segregation.

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Walther, N., Hossain, M. J., Politi, A. Z., Koch, B., Kueblbeck, M., Oedegaard-Fougner, O., Lampe, M., Ellenberg, J.. 2018-01-09. A quantitative map of human Condensins provides new insights into mitotic chromosome architecture. https://doi.org/10.1101/237834

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