| alphaB crystallin is a stress protein and molecular chaperone that has a protective role in cells in response to various types of stress. Structurally, alphaB crystallin is characterized by a conserved immunoglobulin-like compact beta sandwich structure called the 'alpha crystallin core domain'. The self-association of alphaB crystallin subunits results in dynamic multi-subunit polydisperse assemblies. alphaB crystallin co-localizes with filament proteins and models the cytoskeleton framework. alphaB crystallin interacts directly with growth factors and molecules involved in cellular signaling and apoptosis. Under stress, alphaB crystallin recognizes and selectively stabilizes unfolding substrate proteins, preventing their aggregation and protecting cells from cytotoxic aggregates. In this dissertation, sequences involved in the various protein-protein interactions of alphaB crystallin will be identified using a novel technique called protein pin arrays. Structural modeling of the interactive sequences will characterize functional interfaces on the surface of alphaB crystallin subunits that mediate interactions with other small heat shock proteins, unfolding substrates, filaments, and ATP. Biochemical and bioanalytical techniques including ultra-violet circular dichroism spectroscopy, size exclusion chromatography, thermal aggregation assays, and surface plasmon resonance will demonstrate that common sequences in alphaB crystallin mediate complex assembly, filament interactions and chaperone activity. Based on these results, a mechanism for the function of alphaB crystallin including the relationship between complex size, subunit dynamics, and chaperone activity will be proposed. |
