EMD-37713

Single-particle
2.49 Å
EMD-37713 Deposition: 09/10/2023
Map released: 27/12/2023
Last modified: 27/12/2023
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-37713

Small-heat shock protein from Methanocaldococcus jannaschii, Hsp16.5

EMD-37713

Single-particle
2.49 Å
EMD-37713 Deposition: 09/10/2023
Map released: 27/12/2023
Last modified: 27/12/2023
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Methanocaldococcus jannaschii DSM 2661
Sample: Small-heat shock protein from Methanocaldococcus jannaschii, Hsp16.5
Fitted models: 8wp9 (Avg. Q-score: 0.532)

Deposition Authors: Lee J , Ryu B , Kim T , Kim KK
Cryo-EM structure of a 16.5-kDa small heat-shock protein from Methanocaldococcus jannaschii.
Lee J , Ryu B , Kim T , Kim KK
(2024) Int J Biol Macromol , 258 , 128763 - 128774
PUBMED: 38103675
DOI: doi:10.1016/j.ijbiomac.2023.128763
ISSN: 0141-8130
ASTM: IJBMDR
Abstract:
The small heat-shock protein (sHSP) from the archaea Methanocaldococcus jannaschii, MjsHSP16.5, functions as a broad substrate ATP-independent holding chaperone protecting misfolded proteins from aggregation under stress conditions. This protein is the first sHSP characterized by X-ray crystallography, thereby contributing significantly to our understanding of sHSPs. However, despite numerous studies assessing its functions and structures, the precise arrangement of the N-terminal domains (NTDs) within this sHSP cage remains elusive. Here we present the cryo-electron microscopy (cryo-EM) structure of MjsHSP16.5 at 2.49-Å resolution. The subunits of MjsHSP16.5 in the cryo-EM structure exhibit lesser compaction compared to their counterparts in the crystal structure. This structural feature holds particular significance in relation to the biophysical properties of MjsHSP16.5, suggesting a close resemblance to this sHSP native state. Additionally, our cryo-EM structure unveils the density of residues 24-33 within the NTD of MjsHSP16.5, a feature that typically remains invisible in the majority of its crystal structures. Notably, these residues show a propensity to adopt a β-strand conformation and engage in antiparallel interactions with strand β1, both intra- and inter-subunit modes. These structural insights are corroborated by structural predictions, disulfide bond cross-linking studies of Cys-substitution mutants, and protein disaggregation assays. A comprehensive understanding of the structural features of MjsHSP16.5 expectedly holds the potential to inspire a wide range of interdisciplinary applications, owing to the renowned versatility of this sHSP as a nanoscale protein platform.