Centromeres Are Specialized Replication Domains in Heterochromatin

The properties that define centromeres in complex eukaryotes are poorly understood because the underlying DNA is normally repetitive and indistinguishable from surrounding noncentromeric sequences. However, centromeric chromatin contains variant H3-like histones that may specify centromeric regions....

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Autores principales: Ahmad, Kami, Henikoff, Steven
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2001
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2185517/
https://www.ncbi.nlm.nih.gov/pubmed/11285277
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author Ahmad, Kami
Henikoff, Steven
author_facet Ahmad, Kami
Henikoff, Steven
author_sort Ahmad, Kami
collection PubMed
description The properties that define centromeres in complex eukaryotes are poorly understood because the underlying DNA is normally repetitive and indistinguishable from surrounding noncentromeric sequences. However, centromeric chromatin contains variant H3-like histones that may specify centromeric regions. Nucleosomes are normally assembled during DNA replication; therefore, we examined replication and chromatin assembly at centromeres in Drosophila cells. DNA in pericentric heterochromatin replicates late in S phase, and so centromeres are also thought to replicate late. In contrast to expectation, we show that centromeres replicate as isolated domains early in S phase. These domains do not appear to assemble conventional H3-containing nucleosomes, and deposition of the Cid centromeric H3-like variant proceeds by a replication-independent pathway. We suggest that late-replicating pericentric heterochromatin helps to maintain embedded centromeres by blocking conventional nucleosome assembly early in S phase, thereby allowing the deposition of centromeric histones.
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spelling pubmed-21855172008-05-01 Centromeres Are Specialized Replication Domains in Heterochromatin Ahmad, Kami Henikoff, Steven J Cell Biol Original Article The properties that define centromeres in complex eukaryotes are poorly understood because the underlying DNA is normally repetitive and indistinguishable from surrounding noncentromeric sequences. However, centromeric chromatin contains variant H3-like histones that may specify centromeric regions. Nucleosomes are normally assembled during DNA replication; therefore, we examined replication and chromatin assembly at centromeres in Drosophila cells. DNA in pericentric heterochromatin replicates late in S phase, and so centromeres are also thought to replicate late. In contrast to expectation, we show that centromeres replicate as isolated domains early in S phase. These domains do not appear to assemble conventional H3-containing nucleosomes, and deposition of the Cid centromeric H3-like variant proceeds by a replication-independent pathway. We suggest that late-replicating pericentric heterochromatin helps to maintain embedded centromeres by blocking conventional nucleosome assembly early in S phase, thereby allowing the deposition of centromeric histones. The Rockefeller University Press 2001-04-02 /pmc/articles/PMC2185517/ /pubmed/11285277 Text en © 2001 The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Original Article
Ahmad, Kami
Henikoff, Steven
Centromeres Are Specialized Replication Domains in Heterochromatin
title Centromeres Are Specialized Replication Domains in Heterochromatin
title_full Centromeres Are Specialized Replication Domains in Heterochromatin
title_fullStr Centromeres Are Specialized Replication Domains in Heterochromatin
title_full_unstemmed Centromeres Are Specialized Replication Domains in Heterochromatin
title_short Centromeres Are Specialized Replication Domains in Heterochromatin
title_sort centromeres are specialized replication domains in heterochromatin
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2185517/
https://www.ncbi.nlm.nih.gov/pubmed/11285277
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