Building the atomic model for the bacterial flagellar filament by electron cryomicroscopy and image analysis.
The bacterial flagellar filament is a helical propeller for bacterial locomotion. It is a well-ordered helical assembly of a single protein, flagellin, and its tubular structure is formed by 11 protofilaments, each in either of the two distinct conformations, L- and R-type, for supercoiling. We have been studying the three-dimensional structures of the flagellar filaments by electron cryomicroscopy and recently obtained a density map of the R-type filament up to 4 angstroms resolution from an image data set containing only about 41,000 molecular images. The density map showed the features of the alpha-helical backbone and some large side chains, which allowed us to build the complete atomic model as one of the first atomic models of macromolecules obtained solely by electron microscopy image analysis (Yonekura et al., 2003a). We briefly review the structure and the structure analysis, and point out essential techniques that have made this analysis possible.
Yonekura
Koji
K
The W.M. Keck Advanced Microscopy Laboratory, Department of Biochemistry and Biophysics, University of California, San Francisco, 1700 4th Street, San Francisco, California 94158, USA. koji@msg.ucsf.edu
Maki-Yonekura
Saori
S
Namba
Keiichi
K
D020285:Cryoelectron Microscopy; D005408:Flagellin / Q000737:chemistry*; D021621:Imaging, Three-Dimensional; D008958:Models, Molecular; D011487:Protein Conformation; D012486:Salmonella typhimurium / Q000378:metabolism
D005408:Flagellin