PMID: 22143763

Authors:

Braun N, Zacharias M, Peschek J, Kastenmuller A, Zou J, Hanzlik M, Haslbeck M, Rappsilber J, Buchner J, Weinkauf S

Title:

Multiple molecular architectures of the eye lens chaperone alphaB-crystallin elucidated by a triple hybrid approach.

Journal:

Proc Natl Acad Sci U S A. 2011 Dec 20;108(51):20491-6. Epub 2011 Dec 5.

Abstract:

The molecular chaperone alphaB-crystallin, the major player in maintaining the transparency of the eye lens, prevents stress-damaged and aging lens proteins from aggregation. In nonlenticular cells, it is involved in various neurological diseases, diabetes, and cancer. Given its structural plasticity and dynamics, structure analysis of alphaB-crystallin presented hitherto a formidable challenge. Here we present a pseudoatomic model of a 24-meric alphaB-crystallin assembly obtained by a triple hybrid approach combining data from cryoelectron microscopy, NMR spectroscopy, and structural modeling. The model, confirmed by cross-linking and mass spectrometry, shows that the subunits interact within the oligomer in different, defined conformations. We further present the molecular architectures of additional well-defined alphaB-crystallin assemblies with larger or smaller numbers of subunits, provide the mechanism how "heterogeneity" is achieved by a small set of defined structural variations, and analyze the factors modulating the oligomer equilibrium of alphaB-crystallin and thus its chaperone activity.