title: Non-helical perturbations of the flagellar filament: Salmonella typhimurium SJW117 at 9.6 A resolution.
abstract: Using a liquid-helium-cooled superconducting electron cryo-microscope, we obtained low-dose images of negatively stained preparations at 4 K and collected structural data to 1/9.6 -1 for flagellar filaments from the strain SJW117 of Salmonella typhimurium (serotype gt). The subunits of this left-handed, straight filament are non-helically perturbed in a pairwise manner. The perturbation corresponds to an alternating conformation in every other row of subunits. These are the 5-start rows and, necessarily, the resulting structure has a seam. The perturbation is not confined to the outside but extends into the structure. We separated the non-symmetric and symmetric parts of the structural data and generated a three-dimensional reconstruction from the latter. The resulting density map is a structure similar in domain organization to the left-handed filament of S. typhimurium SJW1660. Filtered images generated from the non-symmetric component show an ordered and polar structure. The nature of the perturbation was analyzed by model building using a sphere to represent the subunit at low resolution. A lateral shift of approximately 10 degrees mimics the perturbation.
authors.affiliation: Department of Membrane and Ultrastructure Research, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.
authors.forename: S
authors.initials: S
authors.lastname: Trachtenberg
authors.forename: D J
authors.initials: DJ
authors.lastname: DeRosier
authors.forename: F
authors.initials: F
authors.lastname: Zemlin
authors.forename: E
authors.initials: E
authors.lastname: Beckmann
mesh_terms: D005407:Flagella / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure*; D005408:Flagellin / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure; D005583:Fourier Analysis; D007091:Image Processing, Computer-Assisted; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D009154:Mutation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D012486:Salmonella typhimurium / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure*; D014027:Tobacco Mosaic Virus / Q000737:chemistry / Q000648:ultrastructure
chemical_list: D046911:Macromolecular Substances; D005408:Flagellin