6L6M

HSP18.5 from E. histolytica

Summary for 6L6M

• Entry DOI: 10.2210/pdb6l6m/pdb
• Descriptor: Heat shock protein hsp20 family putative (1 entity in total)
• Functional Keywords: small heat shock protein hsp18.5 molecular chaperone e. histolytica, chaperone
• Biological source: Entamoeba histolytica
• Total number of polymer chains: 4
• Total formula weight: 75393.57

Authors

Kurre, D.,Suguna, K. (deposition date: 2019-10-29, release date: 2020-11-04, Last modification date: 2023-11-22)

Primary citation

Kurre, D.,Suguna, K.
Network of Entamoeba histolytica HSP18.5 dimers formed by two overlapping [IV]-X-[IV] motifs.
Proteins, 2021

PubMed Abstract: Small heat shock proteins (sHSPs) are ATP-independent molecular chaperones with low molecular weight that prevent the aggregation of proteins during stress conditions and maintain protein homeostasis in the cell. sHSPs exist in dynamic equilibrium as a mixture of oligomers of various sizes with a constant exchange of subunits between them. Many sHSPs form cage-like assemblies that may dissociate into smaller oligomers during stress conditions. We carried out the functional and structural characterization of a small heat shock protein, HSP18.5, from Entamoeba histolytica (EhHSP18.5). It showed a pH-dependent change in its oligomeric state, which varied from a tetramer to larger than 48-mer. EhHSP18.5 protected Nde I and lysozyme substrates from temperature and chemical stresses, respectively. The crystal structure of EhHSP18.5 was determined at a resolution of 3.28 Å in C222 cell with four subunits in the asymmetric unit forming two non-metazoan sHSP-type dimers. Unlike the reported cage-like structures, EhHSP18.5 formed a network of linear chains of molecules in the crystal. Instead of a single [IV]-X-[IV] motif, EhHSP18.5 has two overlapping I/V-X-I/V sequences at the C-terminus giving rise to novel interactions between the dimers. Negative staining Electron Microscopy images of EhHSP18.5 showed the presence of multiple oligomers: closed structures of various sizes and long tube-like structures.

PubMed: 33792100
DOI: 10.1002/prot.26081

Experimental method

X-RAY DIFFRACTION (3.28000381979 Å)