Elucidating the Electrostatic Interactions of Bovine Gamma‐B Crystallin via Site‐Directed Mutagenesis

Abstract

The proteins that comprise the water-soluble interior of the optic lens are referred to as crystallin proteins, of which three major categories have been identified: alpha (a), beta (b), and gamma (y). Gamma and beta crystallin proteins have been observed to aggregate with time, which can lead to the formation of cataracts, while alpha crystallin limits this formation by removing deformed protein aggregates from solution. Our studies specifically involve the use of bovine yB crystallin, which is the homologue to human yD crystallin. Prior research from our group has generated computer models of the electrostatic interactions between human yD crystallin molecules to identify the specific residues involved in gamma-gamma and gamma-alpha interactions. Here, we describe our work with a site-directed mutant of bovine yB crystallin (D107A), which we propose to govern inter-protein interactions, and more specifically, gamma-alpha interactions. We seek to compare mutant and wild-type proteins using NMR spectroscopy and dynamic light scattering to better understand how individual residues dictate gamma-gamma and gamma-alpha interactions.