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Science. 2017 Jun 23;356(6344):1284-1287. doi: 10.1126/science.aam9702. Epub 2017 May 18.

Mitotic chromosome assembly despite nucleosome depletion in Xenopus egg extracts.

Author information

1
Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan.
2
Department of Life Science, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan.
3
TAK-Circulator Corporation, Bunkyo-ku, Tokyo 113-0033, Japan.
4
Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan.
5
Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan. hiranot@riken.jp.

Abstract

The nucleosome is the fundamental structural unit of eukaryotic chromatin. During mitosis, duplicated nucleosome fibers are organized into a pair of rod-shaped structures (chromatids) within a mitotic chromosome. However, it remains unclear whether nucleosome assembly is indeed an essential prerequisite for mitotic chromosome assembly. We combined mouse sperm nuclei and Xenopus cell-free egg extracts depleted of the histone chaperone Asf1 and found that chromatid-like structures could be assembled even in the near absence of nucleosomes. The resultant "nucleosome-depleted" chromatids contained discrete central axes positive for condensins, although they were more fragile than normal nucleosome-containing chromatids. Combinatorial depletion experiments underscored the central importance of condensins in mitotic chromosome assembly, which sheds light on their functional cross-talk with nucleosomes in this process.

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PMID:
28522692
DOI:
10.1126/science.aam9702
[Indexed for MEDLINE]

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