Sep 15, 2017

Mitotic post-translational modifications of histones promote chromatin compaction in vitro

Open Biology
Alisa ZhitenevaWilliam C Earnshaw


How eukaryotic chromosomes are compacted during mitosis has been a leading question in cell biology since the nineteenth century. Non-histone proteins such as condensin complexes contribute to chromosome shaping, but appear not to be necessary for mitotic chromatin compaction. Histone modifications are known to affect chromatin structure. As histones undergo major changes in their post-translational modifications during mitotic entry, we speculated that the spectrum of cell-cycle-specific histone modifications might contribute to chromosome compaction during mitosis. To test this hypothesis, we isolated core histones from interphase and mitotic cells and reconstituted chromatin with them. We used mass spectrometry to show that key post-translational modifications remained intact during our isolation procedure. Light, atomic force and transmission electron microscopy analysis showed that chromatin assembled from mitotic histones has a much greater tendency to aggregate than chromatin assembled from interphase histones, even under low magnesium conditions where interphase chromatin remains as separate beads-on-a-string structures. These observations are consistent with the hypothesis that mitotic chromosome formation is a two-sta...Continue Reading

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Mentioned in this Paper

Isolation Procedure
Cations, Divalent
Histone antigen
Magnesium Measurement
Post-Translational Protein Processing
Science of Morphology
Lymphoid Cells
Mitotic Chromosomal Process
SPT6 Protein

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