ジャーナル: EMBO J / 年: 2001 タイトル: The DnaB.DnaC complex: a structure based on dimers assembled around an occluded channel. 著者: M Bárcena / T Ruiz / L E Donate / S E Brown / N E Dixon / M Radermacher / J M Carazo / 要旨: Replicative helicases are motor proteins that unwind DNA at replication forks. Escherichia coli DnaB is the best characterized member of this family of enzymes. We present the 26 A resolution three- ...Replicative helicases are motor proteins that unwind DNA at replication forks. Escherichia coli DnaB is the best characterized member of this family of enzymes. We present the 26 A resolution three-dimensional structure of the DnaB hexamer in complex with its loading partner, DnaC, obtained from cryo-electron microscopy. Analysis of the volume brings insight into the elaborate way the two proteins interact, and provides a structural basis for control of the symmetry state and inactivation of the helicase by DnaC. The complex is arranged on the basis of interactions among DnaC and DnaB dimers. DnaC monomers are observed for the first time to arrange as three dumb-bell-shaped dimers that interlock into one of the faces of the helicase. This could be responsible for the freezing of DnaB in a C(3) architecture by its loading partner. The central channel of the helicase is almost occluded near the end opposite to DnaC, such that even single-stranded DNA could not pass through. We propose that the DnaB N-terminal domain is located at this face.
ダウンロード / ファイル: emd_1017.map.gz / 形式: CCP4 / 大きさ: 7.8 MB / タイプ: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES)
ボクセルのサイズ
X=Y=Z: 3.6 Å
密度
表面レベル
1: 0.00411 / ムービー #1: 0.012
最小 - 最大
-0.0212883 - 0.0298335
平均 (標準偏差)
0.0000559347 (±0.0016241)
対称性
空間群: 1
詳細
EMDB XML:
マップ形状
Axis order
X
Y
Z
Origin
0
0
0
サイズ
128
128
128
Spacing
128
128
128
セル
A=B=C: 460.8 Å α=β=γ: 90 °
CCP4マップ ヘッダ情報:
mode
Image stored as Reals
Å/pix. X/Y/Z
3.6
3.6
3.6
M x/y/z
128
128
128
origin x/y/z
0.000
0.000
0.000
length x/y/z
460.800
460.800
460.800
α/β/γ
90.000
90.000
90.000
MAP C/R/S
1
2
3
start NC/NR/NS
0
0
0
NC/NR/NS
128
128
128
D min/max/mean
-0.021
0.030
0.000
-
添付データ
-
試料の構成要素
-
全体 : DnaB.DnaC complex from Escherichia coli
全体
名称: DnaB.DnaC complex from Escherichia coli
要素
試料: DnaB.DnaC complex from Escherichia coli
タンパク質・ペプチド: DnaB
タンパク質・ペプチド: DnaC
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超分子 #1000: DnaB.DnaC complex from Escherichia coli
超分子
名称: DnaB.DnaC complex from Escherichia coli / タイプ: sample / ID: 1000 集合状態: one homohexamer of DnaB binds to six monomers of DnaC Number unique components: 2