ジャーナル: Proc Natl Acad Sci U S A / 年: 2011 タイトル: Structural dependence of HET-s amyloid fibril infectivity assessed by cryoelectron microscopy. 著者: Naoko Mizuno / Ulrich Baxa / Alasdair C Steven / 要旨: HET-s is a prion protein of the fungus Podospora anserina which, in the prion state, is active in a self/nonself recognition process called heterokaryon incompatibility. Its prionogenic properties ...HET-s is a prion protein of the fungus Podospora anserina which, in the prion state, is active in a self/nonself recognition process called heterokaryon incompatibility. Its prionogenic properties reside in the C-terminal "prion domain." The HET-s prion domain polymerizes in vitro into amyloid fibrils whose properties depend on the pH of assembly; above pH 3, infectious singlet fibrils are produced, and below pH 3, noninfectious triplet fibrils. To investigate the correlation between structure and infectivity, we performed cryo-EM analyses. Singlet fibrils have a helical pitch of approximately 410 Å and a left-handed twist. Triplet fibrils have three protofibrils whose lateral dimensions (36 × 25 Å) and axial packing (one subunit per 9.4 Å) match those of singlets but differ in their supercoiling. At 8.5-Å resolution, the cross-section of the singlet fibril reconstruction is largely consistent with that of a β-solenoid model previously determined by solid-state NMR. Reconstructions of the triplet fibrils show three protofibrils coiling around a common axis and packed less tightly at pH 3 than at pH 2, eventually peeling off. Taken together with the earlier observation that fragmentation of triplet fibrils by sonication does not increase infectivity, these observations suggest a novel mechanism for self-propagation, whereby daughter fibrils nucleate on the lateral surface of singlet fibrils. In triplets, this surface is occluded, blocking nucleation and thereby explaining their lack of infectivity.
A: 73.6 Å / B: 75.44 Å / C: 207.92 Å α=β=γ: 90.0 °
CCP4マップ ヘッダ情報:
mode
Image stored as Reals
Å/pix. X/Y/Z
1.84
1.84
1.84
M x/y/z
40
41
113
origin x/y/z
0.000
0.000
0.000
length x/y/z
73.600
75.440
207.920
α/β/γ
90.000
90.000
90.000
start NX/NY/NZ
-108
-108
-54
NX/NY/NZ
108
108
54
MAP C/R/S
1
2
3
start NC/NR/NS
10
10
-1
NC/NR/NS
40
41
113
D min/max/mean
0.000
0.026
0.004
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添付データ
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試料の構成要素
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全体 : HET-s prion domain (218-289) assembled at pH3
全体
名称: HET-s prion domain (218-289) assembled at pH3
要素
試料: HET-s prion domain (218-289) assembled at pH3
タンパク質・ペプチド: Heterokaryon incompatibility protein s
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超分子 #1000: HET-s prion domain (218-289) assembled at pH3
超分子
名称: HET-s prion domain (218-289) assembled at pH3 / タイプ: sample / ID: 1000 集合状態: helical polymer with a rise of 9.4 A per protein unit Number unique components: 1
分子量
実験値: 8 KDa
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分子 #1: Heterokaryon incompatibility protein s
分子
名称: Heterokaryon incompatibility protein s / タイプ: protein_or_peptide / ID: 1 / Name.synonym: HET-s 詳細: HET-s proteins are assembled to make a single strand helix, with a rise of 9.4 A per protein. 集合状態: Helical filament / 組換発現: Yes