Effect of Betaine and Arginine on Interaction of alpha B-Crystallin with Glycogen Phosphorylase b

Protein-protein interactions (PPIs) play an important role in many biological processes in a living cell. Among them chaperone-client interactions are the most important. In this work PPIs of alpha B-crystallin and glycogen phosphorylase b (Phb) in the presence of betaine (Bet) and arginine (Arg) at 48 degrees C and ionic strength of 0.15 M were studied using methods of dynamic light scattering, differential scanning calorimetry, and analytical ultracentrifugation. It was shown that Bet enhanced, while Arg reduced both the stability of alpha B-crystallin and its adsorption capacity (AC(0)) to the target protein at the stage of aggregate growth. Thus, the anti-aggregation activity of alpha B-crystallin increased in the presence of Bet and decreased under the influence of Arg, which resulted in inhibition or acceleration of Phb aggregation, respectively. Our data show that chemical chaperones can influence the tertiary and quaternary structure of both the target protein and the protein chaperone. The presence of the substrate protein also affects the quaternary structure of alpha B-crystallin, causing its disassembly. This is inextricably linked to the anti-aggregation activity of alpha B-crystallin, which in turn affects its PPI with the target protein. Thus, our studies contribute to understanding the mechanism of interaction between chaperones and proteins.