Solid-state NMR and SAXS studies provide a structural basis for the activation of alphaB-crystallin oligomers.Jehle, S., Rajagopal, P., Bardiaux, B., Markovic, S., Kuhne, R., Stout, J.R., Higman, V.A., Klevit, R.E., van Rossum, B.J., Oschkinat, H.
(2010) Nat Struct Mol Biol 17: 1037-1042
- PubMed: 20802487
- DOI: https://doi.org/10.1038/nsmb.1891
- Primary Citation of Related Structures:
- PubMed Abstract:
The small heat shock protein alphaB-crystallin (alphaB) contributes to cellular protection against stress. For decades, high-resolution structural studies on oligomeric alphaB have been confounded by its polydisperse nature. Here, we present a structural basis of oligomer assembly and activation of the chaperone using solid-state NMR and small-angle X-ray scattering (SAXS). The basic building block is a curved dimer, with an angle of approximately 121 degrees between the planes of the beta-sandwich formed by alpha-crystallin domains. The highly conserved IXI motif covers a substrate binding site at pH 7.5. We observe a pH-dependent modulation of the interaction of the IXI motif with beta4 and beta8, consistent with a pH-dependent regulation of the chaperone function. N-terminal region residues Ser59-Trp60-Phe61 are involved in intermolecular interaction with beta3. Intermolecular restraints from NMR and volumetric restraints from SAXS were combined to calculate a model of a 24-subunit alphaB oligomer with tetrahedral symmetry.
Leibniz-Institut Für Molekulare Pharmakologie, Berlin, Germany.