Binding determinants of the small heat shock protein, αB-crystallin: recognition of the 'IxI' motif.

Small heat shock proteins (sHSPs) play a central role in protein homeostasis under conditions of stress by binding partly unfolded, aggregate-prone proteins and keeping them soluble. Like many sHSPs, the widely expressed human sHSP, αB-crystallin ('αB'), forms large polydisperse multimeric assemblies. Molecular interactions involved in both sHSP function and oligomer ...
formation remain to be delineated. A growing database of structural information reveals that a central conserved α-crystallin domain (ACD) forms dimeric building blocks, while flanking N- and C-termini direct the formation of larger sHSP oligomers. The most commonly observed inter-subunit interaction involves a highly conserved C-terminal 'IxI/V' motif and a groove in the ACD that is also implicated in client binding. To investigate the inherent properties of this interaction, peptides mimicking the IxI/V motif of αB and other human sHSPs were tested for binding to dimeric αB-ACD. IxI-mimicking peptides bind the isolated ACD at 22°C in a manner similar to interactions observed in the oligomer at low temperature, confirming these interactions are likely to exist in functional αB oligomers.
Mesh Terms:
Amino Acid Motifs, Heat-Shock Proteins, Small, Humans, Nuclear Magnetic Resonance, Biomolecular, Peptides, Protein Binding, Protein Multimerization, Protein Structure, Tertiary, Protein Subunits, Temperature, alpha-Crystallin B Chain
EMBO J.
Date: Dec. 12, 2012
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