protein complex oligomerization / response to salt stress / protein folding chaperone / response to hydrogen peroxide / unfolded protein binding / protein folding / response to heat / protein stabilization / protein-containing complex / identical protein binding / cytoplasm 類似検索 - 分子機能
ジャーナル: Philos Trans R Soc Lond B Biol Sci / 年: 2013 タイトル: Changes in the quaternary structure and function of MjHSP16.5 attributable to deletion of the IXI motif and introduction of the substitution, R107G, in the α-crystallin domain. 著者: Roy A Quinlan / Yan Zhang / Andrew Lansbury / Ian Williamson / Ehmke Pohl / Fei Sun / 要旨: The archael small heat-shock protein (sHSP), MjHSP16.5, forms a 24-subunit oligomer with octahedral symmetry. Here, we demonstrate that the IXI motif present in the C-terminal domain is necessary for ...The archael small heat-shock protein (sHSP), MjHSP16.5, forms a 24-subunit oligomer with octahedral symmetry. Here, we demonstrate that the IXI motif present in the C-terminal domain is necessary for the oligomerization of MjHSP16.5. Removal increased the in vitro chaperone activity with citrate synthase as the client protein. Less predictable were the effects of the R107G substitution in MjHSP16.5 because of the differences in the oligomerization of metazoan and non-metazoan sHSPs. We present the crystal structure for MjHSP16.5 R107G and compare this with an improved (2.5 Å) crystal structure for wild-type (WT) MjHSP16.5. Although no significant structural differences were found in the crystal, using cryo-electron microscopy, we identified two 24mer species with octahedral symmetry for the WT MjHSP16.5 both at room temperature and at 60°C, all showing two major species with the same diameter of 12.4 nm. Similarly, at room temperature, there are also two kinds of 12.4 nm oligomers for R107G MjHSP16.5, but in the 60°C sample, a larger 24mer species with a diameter of 13.6 nm was observed with significant changes in the fourfold symmetry axis and dimer-dimer interface. This highly conserved arginine, therefore, contributes to the quaternary organization of non-metazoan sHSP oligomers. Potentially, the R107G substitution has functional consequences as R107G MjHSP16.5 was far superior to the WT protein in protecting βL-crystallin against heat-induced aggregation.
A: Small heat shock protein HSP16.5 B: Small heat shock protein HSP16.5 C: Small heat shock protein HSP16.5 D: Small heat shock protein HSP16.5 E: Small heat shock protein HSP16.5 F: Small heat shock protein HSP16.5 G: Small heat shock protein HSP16.5 H: Small heat shock protein HSP16.5
A: Small heat shock protein HSP16.5 B: Small heat shock protein HSP16.5 C: Small heat shock protein HSP16.5 D: Small heat shock protein HSP16.5 E: Small heat shock protein HSP16.5 F: Small heat shock protein HSP16.5 G: Small heat shock protein HSP16.5 H: Small heat shock protein HSP16.5
A: Small heat shock protein HSP16.5 B: Small heat shock protein HSP16.5 C: Small heat shock protein HSP16.5 D: Small heat shock protein HSP16.5 E: Small heat shock protein HSP16.5 F: Small heat shock protein HSP16.5 G: Small heat shock protein HSP16.5 H: Small heat shock protein HSP16.5
A: Small heat shock protein HSP16.5 B: Small heat shock protein HSP16.5 C: Small heat shock protein HSP16.5 D: Small heat shock protein HSP16.5 E: Small heat shock protein HSP16.5 F: Small heat shock protein HSP16.5 G: Small heat shock protein HSP16.5 H: Small heat shock protein HSP16.5
構造決定の手法: 分子置換 / 解像度: 2.85→48.72 Å / Cor.coef. Fo:Fc: 0.959 / Cor.coef. Fo:Fc free: 0.925 / SU B: 16.848 / SU ML: 0.314 / 交差検証法: THROUGHOUT / ESU R Free: 0.394 / 立体化学のターゲット値: MAXIMUM LIKELIHOOD / 詳細: HYDROGENS HAVE BEEN ADDED IN THE RIDING POSITIONS
Rfactor
反射数
%反射
Selection details
Rfree
0.2543
1314
5 %
RANDOM
Rwork
0.19469
-
-
-
all
0.19768
27031
-
-
obs
0.19768
26318
97.38 %
-
溶媒の処理
イオンプローブ半径: 0.8 Å / 減衰半径: 0.8 Å / VDWプローブ半径: 1.4 Å / 溶媒モデル: MASK