Quaternary dynamics of αB-crystallin as a direct consequence of localised tertiary fluctuations in the C-terminus
Baldwin, A.J. and Hilton, G.R. and Lioe, H. and Bagneris, Claire and Benesch, J.L.P. and Kay, L.E. (2011) Quaternary dynamics of αB-crystallin as a direct consequence of localised tertiary fluctuations in the C-terminus. Journal of Molecular Biology 413 (2), pp. 310-320. ISSN 0022-2836.
The majority of proteins exist in vivo within macromolecular assemblies whose functions are dependent on dynamical processes spanning a wide range of timescales. One such assembly is formed by the molecular chaperone αB-crystallin that exists in a variety of exchanging oligomeric states, centred on a mass of approximately 560 kDa. For many macromolecular assemblies, including αB-crystallin, the inherent dynamics, heterogeneity and high mass contribute to difficulties in quantitative studies. Here we demonstrate a strategy based on correlating solution-state nuclear magnetic resonance spectroscopy and mass spectrometry data to characterize simultaneously the organization and dynamics of the polydisperse αB-crystallin ensemble. We show that protomeric dimers assemble into oligomers via the binding of extended C-termini, with each monomer donating and receiving one terminus. Moreover, we establish that the C-termini undergo millisecond fluctuations which regulate the inter-conversion of oligomeric forms. The combined biophysical approach allows construction of an energy profile for a single monomer that completely describes the equilibrium dynamics of the ensemble. It also facilitates an analysis of dynamics spanning the millisecond to hour timescales and secondary to quaternary structural levels and provides an approach for, simultaneously, obtaining detailed structural, thermodynamic and kinetic information on a heterogeneous protein assembly.
|Keyword(s) / Subject(s):||NMR spectroscopy, small heat shock proteins (sHSPs), chaperone, mass spectrometry, relaxation dispersion|
|School:||Birkbeck Schools and Departments > School of Science > Biological Sciences|
|Date Deposited:||08 Aug 2011 08:34|
|Last Modified:||17 Apr 2013 12:21|
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