Nuclear organization of DNA replication initiation proteins in mammalian cells

Masatoshi Fujita, Yukio Ishimi, Hiromu Nakamura, Tohru Kiyono, Tatsuya Tsurumi

研究成果: Contribution to journalArticle査読

67 被引用数 (Scopus)

抄録

Origin recognition complex (ORC), CDC6, and MCM proteins assemble sequentially to form prereplication chromatin. However, their organization remains largely unclear in mammalian cells. Here we show that ORC1 proteins are associated with non-chromatin nuclear structures and assemble in nuclear foci in mammalian cells using an in vivo chemical cross-linking method. CDC6 proteins were also found to assemble in nuclear foci on non-chromatin nuclear structures, although their physical association with ORC1 has been undetectable. In contrast to the situation in yeast cells, CDC6 was found to remain associated with non-chromatin nuclear structures even after cells entered into S phase. Instead, ORC1 proteins were found to be degraded by a proteasome-dependent pathway during S phase. We also found that some ORC2 proteins are associated with non-chromatin nuclear structures like ORC1, although the remainder binds to nuclease-sensitive chromatin. Further analyses indicate that ORC2 physically interacts with ORC1 on non-chromatin nuclear structures. On the other hand, our results suggest that although a small proportion of MCM complexes are loaded onto chromatin regions near ORC foci, most of them are more widely distributed. Possible relations between such organization of prereplication chromatin and complicated origin specification in higher eukaryotic cells are discussed.

本文言語英語
ページ(範囲)10354-10361
ページ数8
ジャーナルJournal of Biological Chemistry
277
12
DOI
出版ステータス出版済み - 3 22 2002
外部発表はい

All Science Journal Classification (ASJC) codes

  • 生化学
  • 分子生物学
  • 細胞生物学

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