ジャーナル: Nat Struct Mol Biol / 年: 2011 タイトル: The structural basis for MCM2-7 helicase activation by GINS and Cdc45. 著者: Alessandro Costa / Ivar Ilves / Nele Tamberg / Tatjana Petojevic / Eva Nogales / Michael R Botchan / James M Berger / 要旨: Two central steps for initiating eukaryotic DNA replication involve loading of the Mcm2-7 helicase onto double-stranded DNA and its activation by GINS-Cdc45. To better understand these events, we ...Two central steps for initiating eukaryotic DNA replication involve loading of the Mcm2-7 helicase onto double-stranded DNA and its activation by GINS-Cdc45. To better understand these events, we determined the structures of Mcm2-7 and the CMG complex by using single-particle electron microscopy. Mcm2-7 adopts two conformations--a lock-washer-shaped spiral state and a planar, gapped-ring form--in which Mcm2 and Mcm5 flank a breach in the helicase perimeter. GINS and Cdc45 bridge this gap, forming a topologically closed assembly with a large interior channel; nucleotide binding further seals off the discontinuity between Mcm2 and Mcm5, partitioning the channel into two smaller pores. Together, our data help explain how GINS and Cdc45 activate Mcm2-7, indicate that Mcm2-7 loading may be assisted by a natural predisposition of the hexamer to form open rings, and suggest a mechanism by which the CMG complex assists DNA strand separation.
超分子 #1000: Drosophila melanogaster CMG complex - APO
超分子
名称: Drosophila melanogaster CMG complex - APO / タイプ: sample / ID: 1000 / 詳細: The sample was monodisperse 集合状態: One Mcm2-7 heterohexamer binds to one GINS heterotetramer and a Cdc45 monomer Number unique components: 11