Insights into the domains required for dimerization and assembly of human αB crystallin.

Protein pin array technology was used to identify subunit-subunit interaction sites in the small heat shock protein (sHSP) αB crystallin. Subunit-subunit interaction sites were defined as consensus sequences that interacted with both human αA crystallin and αB crystallin. The human αB crystallin protein pin array consisted of contiguous and overlapping peptides, eight amino acids in length, immobilized on pins that were in a 96-well ELISA plate format. The interaction of αB crystallin peptides with physiological partner proteins, αA crystallin and αB crystallin, was detected using antibodies and recorded using spectrophotometric absorbance. Five peptide sequences including ₃₇LFPTSTSLSPFYLRPPSF₅₄ in the N terminus, ₇₅FSVNLDVK₈₂ (β3), ₁₃₁LTITSSLS₁₃₈ (β8) and ₁₄₁GVLTVNGP₁₄₈ (β9) that form β strands in the conserved α crystallin core domain, and ₁₅₅PERTIPITREEK₁₆₆ in the C-terminal extension were identified as subunit-subunit interaction sites in human αB crystallin using the novel protein pin array assay. The subunit-subunit interaction sites were mapped to a three-dimensional (3D) homology model of wild-type human αB crystallin that was based on the crystal structure of wheat sHSP16.9 and Methanococcus jannaschi sHSP16.5 (Mj sHSP16.5). The subunit-subunit interaction sites identified and mapped onto the homology model were solvent-exposed and had variable secondary structures ranging from β strands to random coils and short α helices. The subunit-subunit interaction sites formed a pattern of hydrophobic patches on the 3D surface of human αB crystallin. [ABSTRACT FROM AUTHOR]