On the Role of Allosteric Cooperativity in the Regulation of Protein Kinase A and its Implications in Disease

Abstract

First articulated half a century ago, allostery has remained a universal phenomenon and is essential in understanding processes beyond the molecular level, such as cellular signaling and disease. Allostery also referred to as allosteric regulation, is a process by which biological macromolecules transmit the effect of binding at one site to an often distal, functional site, allowing for regulation. To facilitate the modulation of function between sites, allosteric signal is propagated through conserved amino acid residues, often comprising various structural elements of a protein. In general, allosteric communication is of fundamental interest and potentially of high relevance for drug design and protein engineering. Furthermore, the dysfunction of allosteric networks has been implicated in the etiology of human diseases. However, defining these networks of residues that mediate crosstalk between distal sites remains experimentally challenging and thus, poorly characterized. Since allosteric signal propagation relies on subtle conformational rearrangements, nuclear magnetic resonance (NMR) has emerged as an instrumental tool in investigating allosteric communication. This thesis aims to map allosteric networks at atomic resolution to understand how mutations in protein kinase A (PKA) influence allosteric communication to elicit the progression of various disease states. In this work we demonstrate how disease mutations associated with Cushing’s Syndrome and Fibrolamellar Hepatocellular Carcinoma attenuate the allosteric network of PKA, thereby disrupting the finely tuned regulation, specificity, and activation of PKA to generate dysfunctional signaling. The findings of this thesis provide critical insights into the importance of intramolecular allostery in facilitating functional signaling, directly showing how changes in allosteric networks of proteins lead to dysfunction.