Actin functions as a helical polymer, F-actin, but attempts to build an atomic model for this filament have been hampered by the fact that the filament cannot be crystallized and by structural heterogeneity. We have used a direct electron detector, c ...
Actin functions as a helical polymer, F-actin, but attempts to build an atomic model for this filament have been hampered by the fact that the filament cannot be crystallized and by structural heterogeneity. We have used a direct electron detector, cryo-electron microscopy, and the forces imposed on actin filaments in thin films to reconstruct one state of the filament at 4.7 Å resolution, which allows for building a reliable pseudo-atomic model of F-actin. We also report a different state of the filament where actin protomers adopt a conformation observed in the crystal structure of the G-actin-profilin complex with an open ATP-binding cleft. Comparison of the two structural states provides insights into ATP-hydrolysis and filament dynamics. The atomic model provides a framework for understanding why every buried residue in actin has been under intense selective pressure.
Organizational Affiliation:
FEI Company, Nanoport Europe, 5651 GG Eindhoven, the Netherlands.,Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA.,Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA. Electronic address: egelman@virginia.edu.,Institute of Complex Systems, Forschungszentrum Jülich, 52425 Jülich, Germany; Physics Department, University of Düsseldorf, 40225 Düsseldorf, Germany.,Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA. Electronic address: galkinve@evms.edu.
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