ジャーナル: Nat Commun / 年: 2017 タイトル: Cdt1 stabilizes an open MCM ring for helicase loading. 著者: Jordi Frigola / Jun He / Kerstin Kinkelin / Valerie E Pye / Ludovic Renault / Max E Douglas / Dirk Remus / Peter Cherepanov / Alessandro Costa / John F X Diffley / 要旨: ORC, Cdc6 and Cdt1 act together to load hexameric MCM, the motor of the eukaryotic replicative helicase, into double hexamers at replication origins. Here we show that Cdt1 interacts with MCM ...ORC, Cdc6 and Cdt1 act together to load hexameric MCM, the motor of the eukaryotic replicative helicase, into double hexamers at replication origins. Here we show that Cdt1 interacts with MCM subunits Mcm2, 4 and 6, which both destabilizes the Mcm2-5 interface and inhibits MCM ATPase activity. Using X-ray crystallography, we show that Cdt1 contains two winged-helix domains in the C-terminal half of the protein and a catalytically inactive dioxygenase-related N-terminal domain, which is important for MCM loading, but not for subsequent replication. We used these structures together with single-particle electron microscopy to generate three-dimensional models of MCM complexes. These show that Cdt1 stabilizes MCM in a left-handed spiral open at the Mcm2-5 gate. We propose that Cdt1 acts as a brace, holding MCM open for DNA entry and bound to ATP until ORC-Cdc6 triggers ATP hydrolysis by MCM, promoting both Cdt1 ejection and MCM ring closure.
CelldivisioncycleproteinCDT1 / SIC1 indispensable protein 2 / Topoisomerase-A hypersensitive protein 11
分子量: 49483.438 Da / 分子数: 1 / 由来タイプ: 組換発現 詳細: Residues missing in the coordinates were not seen in the electron density. 由来: (組換発現) Saccharomyces cerevisiae (パン酵母) 遺伝子: TAH11, CDT1, SID2, YJR046W, J1641 / 発現宿主: Escherichia coli (大腸菌) / 参照: UniProt: P47112
プロトコル: SINGLE WAVELENGTH / 単色(M)・ラウエ(L): M / 散乱光タイプ: x-ray
放射波長
波長: 0.97856 Å / 相対比: 1
反射
解像度: 2.15→42 Å / Num. obs: 28350 / % possible obs: 98.7 % / 冗長度: 5.8 % / Rmerge(I) obs: 0.098 / Net I/σ(I): 13.1
反射 シェル
解像度: 2.15→2.26 Å / 冗長度: 5.8 % / Rmerge(I) obs: 1.06 / Mean I/σ(I) obs: 2 / % possible all: 95.4
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解析
ソフトウェア
名称
バージョン
分類
PHENIX
1.8.2_1309
精密化
XDS
データ削減
Aimless
データスケーリング
PHASER
位相決定
精密化
構造決定の手法: 分子置換 開始モデル: the structure i'm depositing with this one - that was solved by SAD (SeMet) - sorry i don't have a pdb code yet... 解像度: 2.152→41.948 Å / SU ML: 0.26 / 交差検証法: FREE R-VALUE / σ(F): 1.36 / 位相誤差: 28.87