Tensile Mechanics of Coiled Coil Protein Structures

Abstract

A coiled-coil protein structure consists of two or more interacting α-helical strands that together form a supercoil structure. Coiled-coil structures entail unique mechanical properties that are critical to the function and integrity of various motor proteins, cytoskeletal filaments and extra-cellular matrix proteins. Here we present a thermodynamic model to predict the mechanical properties of a given coiled-coil structural motif. Within the proposed model we identify and quantify various energetic and entropic effects, responsible for dimerization of two helical polypeptides into a coiled coil structure. We determine our model parameters by examining a large body of solved protein structures that contain coiled coil motifs. This would allow us to develop a thermodynamic model for predicting the propensity of given amino acid sequence to form a coiled coil structure. Further incorporation of the above model into our previously developed α-helix tensile mechanics model would enable us to predict the structural response of a given coiled coil motif to a tensile stress.