Multiple Sites in alpha B-Crystallin Modulate Its Interactions with Desmin Filaments Assembled In Vitro

Houck, Scott A.; Landsbury, Andrew; Clark, John I.; Quinlan, Roy A.

Abstract

The β3- and β8-strands and C-terminal residues 155–165 of αB-crystallin were identified by pin arrays as interaction sites for various client proteins including the intermediate filament protein desmin. Here we present data using 5 well-characterised αB-crystallin protein constructs with substituted β3- and β8-strands and with the C-terminal residues 155–165 deleted to demonstrate the importance of these sequences to the interaction of αB-crystallin with desmin filaments. We used electron microscopy of negatively stained samples to visualize increased interactions followed by sedimentation assays to quantify our observations. A low-speed sedimentation assay measured the ability of αB-crystallin to prevent the self-association of desmin filaments. A high-speed sedimentation assay measured αB-crystallin cosedimentation with desmin filaments. Swapping the β8-strand of αB-crystallin or deleting residues 155–165 increased the cosedimentation of αB-crystallin with desmin filaments, but this coincided with increased filament-filament interactions. In contrast, substitution of the β3-strand with the equivalent αA-crystallin sequences improved the ability of αB-crystallin to prevent desmin filament-filament interactions with no significant change in its cosedimentation properties. These data suggest that all three sequences (β3-strand, β8-strand and C-terminal residues 155–165) contribute to the interaction of αB-crystallin with desmin filaments. The data also suggest that the cosedimentation of αB-crystallin with desmin filaments does not necessarily correlate with preventing desmin filament-filament interactions. This important observation is relevant not only to the formation of the protein aggregates that contain both desmin and αB-crystallin and typify desmin related myopathies, but also to the interaction of αB-crystallin with other filamentous protein polymers.

Citation

Houck, S. A., Landsbury, A., Clark, J. I., & Quinlan, R. A. (2011). Multiple Sites in alpha B-Crystallin Modulate Its Interactions with Desmin Filaments Assembled In Vitro. PLoS ONE, 6(11), Article e25859. https://doi.org/10.1371/journal.pone.0025859

• Journal Article Type: Article
• Acceptance Date: Sep 13, 2011
• Online Publication Date: Nov 9, 2011
• Publication Date: Nov 9, 2011
• Deposit Date: Apr 23, 2012
• Publicly Available Date: Jun 8, 2012
• Journal: PLoS ONE
• Publisher: Public Library of Science
• Peer Reviewed: Peer Reviewed
• Volume: 6
• Issue: 11
• Article Number: e25859
• DOI: https://doi.org/10.1371/journal.pone.0025859