Cookies

We use cookies to ensure that we give you the best experience on our website. By continuing to browse this repository, you give consent for essential cookies to be used. You can read more about our Privacy and Cookie Policy.


Durham Research Online
You are in:

Changes in the quaternary structure and function of MjHSP16.5 attributable to deletion of the I–X–I motif and introduction of the substitution, R107G in the a-crystallin domain.

Quinlan, R.A. and Zhang, Y. and Lansbury, A. and Williamson, I. and Pohl, E. and Sun, F. (2013) 'Changes in the quaternary structure and function of MjHSP16.5 attributable to deletion of the I–X–I motif and introduction of the substitution, R107G in the a-crystallin domain.', Philosophical transactions of the Royal Society B : biological sciences., 368 (1617). p. 20120327.

Abstract

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.

Item Type:Article
Keywords:Chaperone/small heat-shock proteins, Desminopathy/crystallinopathy, IXI motif, Structure and function, CRYAB/αB-crystallin/R120G, Cryo-electron microscopy.
Full text:(VoR) Version of Record
Download PDF
(2180Kb)
Status:Peer-reviewed
Publisher Web site:http://dx.doi.org/10.1098/rstb.2012.0327
Publisher statement:© 2013 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0/, which permits unrestricted use, provided the original author and source are credited.
Date accepted:No date available
Date deposited:03 January 2014
Date of first online publication:2013
Date first made open access:No date available

Save or Share this output

Export:
Export
Look up in GoogleScholar