(526a) Energy Flow As a Mechanism for Signal Propagation in Proteins

Proteins are characterized by a multitude of interatomic interactions that ultimately determine their macroscopic behavior. This balance of interactions renders such molecules susceptible to subtle perturbations which, in several cases, can result in significant changes in structure or function. In addition, the resulting changes in structure or function can be non-local in character, with allostery and other signaling processes being a prime example of global changes triggered by local perturbations. Understanding how these processes occur in the microscopic level is a major goal of current biochemical research. Here, we provide a detailed account of total energy flow in two proteins and discuss the consequences of our findings for allostery and signal propagation in proteins.

We have analyzed energy transfer in different structures of an intrinsically disordered (ID) protein, and show that the efficiency of energy propagation is not tied to the compactness of the structure or the number of tertiary contacts. This indicates that energy propagation through the protein backbone is a viable mechanism for signal propagation in intrinsically disordered proteins. In addition, we analyzed energy transfer in the catabolite activator protein (CAP), an allosteric protein that operates in the absence of conformational changes. We found that energy propagation is more efficient for the wild type (allosterically active), when compared to the allosterically inactive mutant D138V. These two examples demonstrate the feasibility of using energy flow through strongly interacting residues as a measure of efficiency of signal propagation in proteins.