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

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.

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

10.1101/237834 ◽

2018 ◽

Cited By ~ 1

Author(s):

Nike Walther ◽

M. Julius Hossain ◽

Antonio Z. Politi ◽

Birgit Koch ◽

Moritz Kueblbeck ◽

...

Keyword(s):

Mitotic Chromosome ◽

Super Resolution ◽

Maximum Size ◽

Correlation Spectroscopy ◽

Loop Model ◽

Chromosome Architecture ◽

Fluorescence Correlation ◽

Chromatid Segregation ◽

Early Anaphase ◽

Super Resolution Microscopy

AbstractThe 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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C. elegans condensin promotes mitotic chromosome architecture, centromere organization, and sister chromatid segregation during mitosis and meiosis

Genes & Development ◽

10.1101/gad.968302 ◽

2002 ◽

Vol 16 (6) ◽

pp. 729-742 ◽

Cited By ~ 187

Author(s):

K. A. Hagstrom

Keyword(s):

Sister Chromatid ◽

Mitotic Chromosome ◽

Chromosome Architecture ◽

C Elegans ◽

Chromatid Segregation ◽

Mitosis And Meiosis

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Faculty Opinions recommendation of C. elegans condensin promotes mitotic chromosome architecture, centromere organization, and sister chromatid segregation during mitosis and meiosis.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1006200.122157 ◽

2002 ◽

Author(s):

Robert K Herman

Keyword(s):

Sister Chromatid ◽

Mitotic Chromosome ◽

Chromosome Architecture ◽

C Elegans ◽

Chromatid Segregation ◽

Mitosis And Meiosis

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Enzyme leaps fuel antichemotaxis

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1717844115 ◽

2017 ◽

Vol 115 (1) ◽

pp. 14-18 ◽

Cited By ~ 57

Author(s):

Ah-Young Jee ◽

Sandipan Dutta ◽

Yoon-Kyoung Cho ◽

Tsvi Tlusty ◽

Steve Granick

Keyword(s):

Foraging Strategy ◽

Correlation Spectroscopy ◽

Stimulated Emission ◽

Product Concentration ◽

Active Materials ◽

Superresolution Microscopy ◽

Fluorescence Correlation ◽

Transit Times ◽

Catalytically Active ◽

Run And Tumble

There is mounting evidence that enzyme diffusivity is enhanced when the enzyme is catalytically active. Here, using superresolution microscopy [stimulated emission-depletion fluorescence correlation spectroscopy (STED-FCS)], we show that active enzymes migrate spontaneously in the direction of lower substrate concentration (“antichemotaxis”) by a process analogous to the run-and-tumble foraging strategy of swimming microorganisms and our theory quantifies the mechanism. The two enzymes studied, urease and acetylcholinesterase, display two families of transit times through subdiffraction-sized focus spots, a diffusive mode and a ballistic mode, and the latter transit time is close to the inverse rate of catalytic turnover. This biochemical information-processing algorithm may be useful to design synthetic self-propelled swimmers and nanoparticles relevant to active materials. Executed by molecules lacking the decision-making circuitry of microorganisms, antichemotaxis by this run-and-tumble process offers the biological function to homogenize product concentration, which could be significant in situations when the reactant concentration varies from spot to spot.

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