5NMS

Hsp21 dodecamer, structural model based on cryo-EM and homology modelling

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5NMS の概要

• エントリーDOI: 10.2210/pdb5nms/pdb
• EMDBエントリー: 3459
• 分子名称: 25.3 kDa heat shock protein, chloroplastic (2 entities in total)
• 機能のキーワード: stress response, heat shock protein, chaperone, all-beta greek key
• 由来する生物種: Arabidopsis thaliana (Mouse-ear cress); 詳細
• 細胞内の位置: Plastid, chloroplast : P31170 P31170
• タンパク質・核酸の鎖数: 12
• 化学式量合計: 169027.29

構造登録者

Rutsdottir, G.,Harmark, J.,Koeck, P.J.B.,Hebert, H.,Soderberg, C.A.G.,Emanuelsson, C. (登録日: 2017-04-07, 公開日: 2017-05-03, 最終更新日: 2024-05-08)

主引用文献

Rutsdottir, G.,Harmark, J.,Weide, Y.,Hebert, H.,Rasmussen, M.I.,Wernersson, S.,Respondek, M.,Akke, M.,Hjrup, P.,Koeck, P.J.B.,Soderberg, C.A.G.,Emanuelsson, C.
Structural model of dodecameric heat-shock protein Hsp21: Flexible N-terminal arms interact with client proteins while C-terminal tails maintain the dodecamer and chaperone activity.
J. Biol. Chem., 292:8103-8121, 2017

PubMed Abstract: Small heat-shock proteins (sHsps) prevent aggregation of thermosensitive client proteins in a first line of defense against cellular stress. The mechanisms by which they perform this function have been hard to define due to limited structural information; currently, there is only one high-resolution structure of a plant sHsp published, that of the cytosolic Hsp16.9. We took interest in Hsp21, a chloroplast-localized sHsp crucial for plant stress resistance, which has even longer N-terminal arms than Hsp16.9, with a functionally important and conserved methionine-rich motif. To provide a framework for investigating structure-function relationships of Hsp21 and understanding these sequence variations, we developed a structural model of Hsp21 based on homology modeling, cryo-EM, cross-linking mass spectrometry, NMR, and small-angle X-ray scattering. Our data suggest a dodecameric arrangement of two trimer-of-dimer discs stabilized by the C-terminal tails, possibly through tail-to-tail interactions between the discs, mediated through extended IVI motifs. Our model further suggests that six N-terminal arms are located on the outside of the dodecamer, accessible for interaction with client proteins, and distinct from previous undefined or inwardly facing arms. To test the importance of the IVI motif, we created the point mutant V181A, which, as expected, disrupts the Hsp21 dodecamer and decreases chaperone activity. Finally, our data emphasize that sHsp chaperone efficiency depends on oligomerization and that client interactions can occur both with and without oligomer dissociation. These results provide a generalizable workflow to explore sHsps, expand our understanding of sHsp structural motifs, and provide a testable Hsp21 structure model to inform future investigations.

PubMed: 28325834
DOI: 10.1074/jbc.M116.766816

実験手法

ELECTRON MICROSCOPY (10 Å)