Exploring the 3D molecular architecture of Escherichia coli type 1 pili.
An integrated approach combining information gained by Fourier transformation, linear Markham superposition (real space) and mass-per-length measurement by scanning transmission electron microscopy was used to analyze the helical structure of the rod-like type 1 pili expressed by uropathogenic Escherichia coli strain W3110. The 3D reconstruction calculated from the experimental data showed the pili to be 6.9nm wide, right-handed helical tubes with a 19.31(+/-0.34)nm long helical repeat comprising 27 FimA monomers associated head-to-tail in eight turns of the genetic one-start helix. Adjacent turns of the genetic helix are connected via three binding sites making the pilus rod rather stiff. In situ immuno-electron microscopy experiments showed the minor subunit (FimH) mediating pilus adhesion to bladder epithelial cells to be the distal protein of the pilus tip, which had a spring-like appearance at higher magnification. The subunits FimG and FimF connect FimH to the FimA rod, the sequential orientation being FimA-FimF-FimG-FimH. The electron density map calculated at 18A resolution from an atomic model of the pilus rod (built using the pilin domain FimH together with the G1 strand of FimC as a template for FimA and applying the optimal helical parameters determined to the head-to-tail interaction model for pilus assembly) was practically identical with that of the actual 3D reconstruction.
Hahn
Erik
E
Institute of Veterinary Anatomy, University of Zürich, Switzerland.
Wild
Peter
P
Hermanns
Uta
U
Sebbel
Peter
P
Glockshuber
Rudi
R
Häner
Marcus
M
Taschner
Nicole
N
Burkhard
Peter
P
Aebi
Ueli
U
Müller
Shirley A
SA
D018830:Adhesins, Escherichia coli / Q000737:chemistry / Q000648:ultrastructure; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000737:chemistry / Q000648:ultrastructure; D010450:Endopeptidases; D004926:Escherichia coli / Q000737:chemistry* / Q000472:pathogenicity / Q000502:physiology / Q000648:ultrastructure*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000648:ultrastructure; D036781:Fimbriae Proteins / Q000737:chemistry / Q000648:ultrastructure; D010861:Fimbriae, Bacterial / Q000737:chemistry* / Q000145:classification / Q000648:ultrastructure*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D046911:Macromolecular Substances; D017348:Microscopy, Electron, Scanning Transmission; D016253:Microscopy, Immunoelectron; D008958:Models, Molecular; D021122:Protein Subunits; D014774:Virulence
D018830:Adhesins, Escherichia coli; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D021122:Protein Subunits; C058769:fimH protein, E coli; C063055:fimbrillin; D036781:Fimbriae Proteins; D010450:Endopeptidases; C067127:prepilin peptidase protein, Bacteria