Network of Entamoeba histolytica HSP18.5 dimers formed by two overlapping IV-X-IV motifs

Kurre, D and Suguna, K (2021) Network of Entamoeba histolytica HSP18.5 dimers formed by two overlapping IV-X-IV motifs. In: Proteins: Structure, Function and Bioinformatics .

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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 à in C2221 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. © 2021 Wiley Periodicals LLC.

Item Type:	Journal Article
Publication:	Proteins: Structure, Function and Bioinformatics
Publisher:	John Wiley and Sons Inc
Additional Information:	The copyright for this article belongs to John Wiley and Sons Inc
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	12 Jul 2021 09:35
Last Modified:	12 Jul 2021 09:35
URI:	http://eprints.iisc.ac.in/id/eprint/68825

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