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Licensed Unlicensed Requires Authentication Published by De Gruyter January 18, 2016

Effect of molecular chaperones on aberrant protein oligomers in vitro: super-versus sub-stoichiometric chaperone concentrations

  • Sara Cappelli , Amanda Penco , Benedetta Mannini , Roberta Cascella , Mark R. Wilson , Heath Ecroyd , Xinyi Li , Joel N. Buxbaum , Christopher M. Dobson , Cristina Cecchi , Annalisa Relini and Fabrizio Chiti EMAIL logo
From the journal Biological Chemistry


Living systems protect themselves from aberrant proteins by a network of chaperones. We have tested in vitro the effects of different concentrations, ranging from 0 to 16 μm, of two molecular chaperones, namely αB-crystallin and clusterin, and an engineered monomeric variant of transthyretin (M-TTR), on the morphology and cytotoxicity of preformed toxic oligomers of HypF-N, which represent a useful model of misfolded protein aggregates. Using atomic force microscopy imaging and static light scattering analysis, all were found to bind HypF-N oligomers and increase the size of the aggregates, to an extent that correlates with chaperone concentration. SDS-PAGE profiles have shown that the large aggregates were predominantly composed of the HypF-N protein. ANS fluorescence measurements show that the chaperone-induced clustering of HypF-N oligomers does not change the overall solvent exposure of hydrophobic residues on the surface of the oligomers. αB-crystallin, clusterin and M-TTR can diminish the cytotoxic effects of the HypF-N oligomers at all chaperone concentration, as demonstrated by MTT reduction and Ca2+ influx measurements. The observation that the protective effect is primarily at all concentrations of chaperones, both when the increase in HypF-N aggregate size is minimal and large, emphasizes the efficiency and versatility of these protein molecules.


This work was supported with the ‘Fondi di Ateneo’ of the University of Florence, Italy.


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Received: 2015-9-10
Accepted: 2016-1-11
Published Online: 2016-1-18
Published in Print: 2016-5-1

©2016 by De Gruyter

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