SciCombinator

Discover the most talked about and latest scientific content & concepts.

N Walther, MJ Hossain, AZ Politi, B Koch, M Kueblbeck, Ø Ødegård-Fougner, M Lampe and J Ellenberg
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 (FSC)-calibrated live-cell imaging and superresolution microscopy. Although ∼35,000 Condensin II complexes are stably bound to chromosomes throughout mitosis, ∼195,000 Condensin I complexes dynamically bind in two steps: prometaphase and early anaphase. The two Condensins rarely colocalize 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.
Tweets*
92
Facebook likes*
3
Reddit*
0
News coverage*
0
Blogs*
0
SC clicks
0
Concepts
Metaphase, Meiosis, Anaphase, Cell nucleus, Chromatid, Chromosome, Cell cycle, Mitosis
MeSH headings
-
comments powered by Disqus

* Data courtesy of Altmetric.com