Presentation Title
Interaction of the novel WYR domain of flightin with the myosin rod changes its coiled-coil secondary structure
Abstract
Structural changes in the myosin II light meromyosin (LMM) that influence thick filament mechanical properties and muscle function are modulated by LMM-binding proteins. Flightin (FLN) is an LMM-binding protein that is indispensable for the function of Drosophila indirect flight muscle (IFM); it impacts the viscoelasticity of thick filaments and plays an essential role in sarcomere organization and structural stability. FLN has a three domain structure that includes WYR, a novel 52 amino acid domain conserved throughout Pancrustacea. FLN mutants lacking either the N-terminal or C-terminal domains flanking WYR partially rescue the IFM phenotype of FLN null flies and implicate the conserved WYR domain as essential for FLN function. In this study, we used Circular Dichroism (CD) to: (1) Test the hypothesis that WYR binds the LMM, (2) characterize the secondary structure of WYR, and (3) examine the structural impact WYR has on the LMM. Resultant ellipticity at 260-190nm reveals a structural profile for WYR and supports an interaction with the LMM that coordinates a conformational shift in both binding partners. We find that the secondary structure of WYR displays predominant negative ellipticity at ~190-192nm with a 222/208 ratio of ~0.38, a trademark of a 310 helix. Deconvolution of the CD spectra using various methods are in consensus that 40-50% of WYR is unstructured and contains a portion of beta structure and helical content. WYR in the context of the LMM shows substantial conformation shifts including an increase in the 222/208 ratio that is maximal at a WYR to LMM ratio of 5:2-5:1. While the LMM alone exhibits a 222/208 ratio of 1.1-1.2, in line with previous reports, the LMM experiences a greater 222/208 ratio with increasing WYR concentration. Our results support the hypothesis that WYR binds the LMM and that this interaction brings about structural changes in the coiled-coil.
Primary Faculty Mentor Name
Jim Vigoreaux
Faculty/Staff Collaborators
Neil Wood
Status
Graduate
Student College
College of Arts and Sciences
Program/Major
Biology
Primary Research Category
Biological Sciences
Interaction of the novel WYR domain of flightin with the myosin rod changes its coiled-coil secondary structure
Structural changes in the myosin II light meromyosin (LMM) that influence thick filament mechanical properties and muscle function are modulated by LMM-binding proteins. Flightin (FLN) is an LMM-binding protein that is indispensable for the function of Drosophila indirect flight muscle (IFM); it impacts the viscoelasticity of thick filaments and plays an essential role in sarcomere organization and structural stability. FLN has a three domain structure that includes WYR, a novel 52 amino acid domain conserved throughout Pancrustacea. FLN mutants lacking either the N-terminal or C-terminal domains flanking WYR partially rescue the IFM phenotype of FLN null flies and implicate the conserved WYR domain as essential for FLN function. In this study, we used Circular Dichroism (CD) to: (1) Test the hypothesis that WYR binds the LMM, (2) characterize the secondary structure of WYR, and (3) examine the structural impact WYR has on the LMM. Resultant ellipticity at 260-190nm reveals a structural profile for WYR and supports an interaction with the LMM that coordinates a conformational shift in both binding partners. We find that the secondary structure of WYR displays predominant negative ellipticity at ~190-192nm with a 222/208 ratio of ~0.38, a trademark of a 310 helix. Deconvolution of the CD spectra using various methods are in consensus that 40-50% of WYR is unstructured and contains a portion of beta structure and helical content. WYR in the context of the LMM shows substantial conformation shifts including an increase in the 222/208 ratio that is maximal at a WYR to LMM ratio of 5:2-5:1. While the LMM alone exhibits a 222/208 ratio of 1.1-1.2, in line with previous reports, the LMM experiences a greater 222/208 ratio with increasing WYR concentration. Our results support the hypothesis that WYR binds the LMM and that this interaction brings about structural changes in the coiled-coil.