Molecular Modeling of Averaged Rigor Crossbridges from Tomograms of Insect Flight MuscleChen, L.F., Winkler, H., Reedy, M.K., Reedy, M.C., Taylor, K.A.
(2002) J.Struct.Biol. 138: 92-104
- PubMed: 12160705
- Primary Citation of Related Structures:
- PubMed Abstract:
- The Use of Electron Tomography for Structural Analysis of Disordered Protein Arrays.
Taylor, K.A.,Tang, J.,Cheng, Y.,Winkler, H.
(1997) J.Struct.Biol. 120: 372
- Multivariate Statistical Analysis of Three-Dimensional Cross-Bridge Motifs in Insect Flight Muscle
Winkler, H.,Taylor, K.A.
(1999) Ultramicroscopy 77: 141
- Real Space Refinement of Acto-Myosin Structures from Sectioned Muscle.
Chen, L.F.,Blanc, E.,Chapman, M.S.,Taylor, K.A.
(2001) J.Struct.Biol. 133: 221
Electron tomography, correspondence analysis, molecular model building, and real-space refinement provide detailed 3-D structures for in situ myosin crossbridges in the nucleotide-free state (rigor), thought to represent the end of the power stroke. ...
Electron tomography, correspondence analysis, molecular model building, and real-space refinement provide detailed 3-D structures for in situ myosin crossbridges in the nucleotide-free state (rigor), thought to represent the end of the power stroke. Unaveraged tomograms from a 25-nm longitudinal section of insect flight muscle preserved native structural variation. Recurring crossbridge motifs that repeat every 38.7 nm along the actin filament were extracted from the tomogram and classified by correspondence analysis into 25 class averages, which improved the signal to noise ratio. Models based on the atomic structures of actin and of myosin subfragment 1 were rebuilt to fit 11 class averages. A real-space refinement procedure was applied to quantitatively fit the reconstructions and to minimize steric clashes between domains introduced during the fitting. These combined procedures show that no single myosin head structure can fit all the in situ crossbridges. The validity of the approach is supported by agreement of these atomic models with fluorescent probe data from vertebrate muscle as well as with data from regulatory light chain crosslinking between heads of smooth muscle heavy meromyosin when bound to actin.
Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA.