Stepwise unfolding supports a subunit model for vertebrate kinetochores.

Proc Natl Acad Sci U S A

Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, Scotland, United Kingdom;

Published: March 2017

During cell division, interactions between microtubules and chromosomes are mediated by the kinetochore, a proteinaceous structure located at the primary constriction of chromosomes. In addition to the centromere histone centromere protein A (CENP-A), 15 other members of the constitutive centromere associated network (CCAN) participate in the formation of a chromatin-associated scaffold that supports kinetochore structure. We performed a targeted screen analyzing unfolded centrochromatin from CENP-depleted chromosomes. Our results revealed that CENP-C and CENP-S are critical for the stable folding of mitotic kinetochore chromatin. Multipeak fitting algorithms revealed the presence of an organized pattern of centrochromatin packing consistent with arrangement of CENP-A-containing nucleosomes into up to five chromatin "subunits"-each containing roughly 20-30 nucleosomes. These subunits could be either layers of a boustrophedon or small loops of centromeric chromatin.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5373359PMC
http://dx.doi.org/10.1073/pnas.1614145114DOI Listing

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