Thursday, November 12, 2015: 9:55 AM
255B (Salt Palace Convention Center)
Coiled coils are protein structural motifs made up of two or more α-helices twisted around one another. Coiled coils are critical to the function of various motor proteins and other mechanosensetive protein structures. Dimeric coiled coils in the form of long rigid rods are responsible for mechanical load transmission and act as lever arms and possibly reversible springs within myosin family of proteins. Mechanical properties of the coiled coil structures forming the tail domain of myosin II are crucial to its work cycle. Single molecule studies using atomic force microscopy or optical tweezers along with various molecular simulation studies have confirmed the unique mechanical properties of the coiled coil structures. However, single molecule experimental techniques are not capable of probing the mechanical properties of short coiled coil motifs in their native structural settings and the molecular simulation studies often fail to generate a quantitatively accurate prediction of their response to mechanical load. At the same time both of these methods are time consuming and expensive. Here we present a theoretical 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 thermodynamical 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 bending and tensile stress.