Mammalian Mcm2/4/6/7 complex forms a toroidal structure

Norikazu Yabuta, Naoko Kajimura, Kouta Mayanagi, Michio Sato, Takahito Gotow, Yasuo Uchiyama, Yukio Ishimi, Hiroshi Nojima

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


Background: The Mcm proteins are a family of six homologous proteins (Mcm2-7) that play an important role in DNA replication. They form Mcm4/6/7 and Mcm2/4/6/7 complexes, but their structures are not known. Results: We found that the human Mcm2/4/6/7 tetramer forms a toroidal structure, with a central cavity about 3-4 nm in diameter. Observations were made using electron microscopy, employing the image analysis of single particles. The most predominant averaged image displayed a toroid harbouring four bulges forming corners, one of which was larger than the others. This structure was very similar to the mouse Mcm2/4/6/7 tetramer that was independently prepared and analysed by electron microscopy. These toroidal structures are distinct from that of the Mcm4/6/7 hexamer, which was also examined by electron microscopy. GST(glutathione S-transferase)-pull down and two hybrid experiments suggest that a putative Mcm6-Mcm6 hinge contributes to the formation of the Mcm7/4/6/6/4/7 heterohexamer. Conclusions: The Mcm2/4/6/7 tetramer forms a toroidal structure that is distinct from that of the Mcm4/6/7 hexamer in size and shape.

Original languageEnglish
Pages (from-to)413-421
Number of pages9
JournalGenes to Cells
Issue number5
Publication statusPublished - May 1 2003
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Genetics
  • Cell Biology


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