Role of Protein Dynamics in the Function of p38 Kinase and Protein Tyrosine Phosphatase 1B

Abstract

In order to become highly specific, kinases and phosphatase require a carefully orchestrated mode of action. These modes are driven by both protein conformation and dynamics. Here, we use biomolecular NMR spectroscopy to determine how dynamics influence the catalytic activity, substrate selectivity and allostery in the kinase p38 and the phosphatase PTP1B. The MAPK p38 is a ser/thr protein kinase that is essential for cell differentiation and autophagy. The exact events that lead to p38 activation, however, are not well understood. Thus, we used a variety of NMR relaxation measurements applied to different states of the activation pathway of p38, which includes phosphorylation, substrate, and ATP binding, to understand the activation and regulation of p38. Unexpectedly, our data showed that phosphorylation of p38 is important, but substrate binding is indeed key for the synchronization of the dynamics across the molecule to activate p38. And, it is this synchronization that allows for enhanced ATP recruitment and thus the full activity of p38. The tyrosine phosphatase PTP1B is essential for a variety of cellular processes including glucose metabolism, body mass regulation, and proliferation. We have determined that PTP1B uses rigid conformation changes to achieve its enzymatic activity that can be dynamically modulated by allosteric action. Interestingly, this allostery is mainly driven by dynamic changes. To gain further insights into PTP1B dynamics and to understand how the backbone and side-chain dynamics are correlated, we performed relaxation dispersion measurements to measure the side-chain motions in PTP1B. Here, we present the results of PTP1B side-chain dynamics and show how it regulates its overall function.