TY - JOUR
T1 - Helical perturbations of the flagellar filament
T2 - Rhizobium lupini H13-3 at 13 Å resolution
AU - Cohen-Krausz, Sarah
AU - Trachtenberg, Shlomo
PY - 1998
Y1 - 1998
N2 - Flagellar filaments are highly conserved structures in terms of the underlying symmetry of the polymer, subunit domain organization of the flagellin monomer, amino acid composition and primary sequence at the N and C termini. Traditionally, filaments are classified as 'plain' or 'complex.' In complex filaments, the helical lattice is perturbed in a pairwise manner such that the symmetry is reduced along the 6-start helical lines. Both plain (unperturbed) and complex (helically perturbed) components are helically symmetric and share a common lattice. The perturbation in Rhizobium lupini H13-3 results in a subunit composed of a dimer of flagellin. We have generated a ~ 13 Å resolution three-dimensional density map of the complex filament of R. lupini H13-3 from low-dose images of negatively stained filaments. Compared to a previous map, which extended to only ~25 Å resolution and which was generated from only five filaments containing six layer-lines each, the current map is a product of merging 139 data sets containing 66 layer-lines each. The higher resolution and improved signal- to-noise yield a detailed and interpretable density map. The density map is divided into four concentric rings. These amount to two dense cylinders interconnected by low density radial spokes and wrapped by a three-start external winding. The unperturbed component of the map is strikingly similar to the known plain filament maps and, in particular, to that of Caulobacter crescentus. The helically perturbed component contributes mainly to the filaments's exterior (domain D3) where it comprises the tips of the outer domains interconnecting, pairwise, along the 11-start protofilaments and, again, laterally along the 6-start lines forming vertical and horizontal loops. Strong intersubunit connectivity occurs in the D2 shell and in the inner shell which is dominated by 3-start densities. The contribution of the complex component to the radial spokes seems negligible.
AB - Flagellar filaments are highly conserved structures in terms of the underlying symmetry of the polymer, subunit domain organization of the flagellin monomer, amino acid composition and primary sequence at the N and C termini. Traditionally, filaments are classified as 'plain' or 'complex.' In complex filaments, the helical lattice is perturbed in a pairwise manner such that the symmetry is reduced along the 6-start helical lines. Both plain (unperturbed) and complex (helically perturbed) components are helically symmetric and share a common lattice. The perturbation in Rhizobium lupini H13-3 results in a subunit composed of a dimer of flagellin. We have generated a ~ 13 Å resolution three-dimensional density map of the complex filament of R. lupini H13-3 from low-dose images of negatively stained filaments. Compared to a previous map, which extended to only ~25 Å resolution and which was generated from only five filaments containing six layer-lines each, the current map is a product of merging 139 data sets containing 66 layer-lines each. The higher resolution and improved signal- to-noise yield a detailed and interpretable density map. The density map is divided into four concentric rings. These amount to two dense cylinders interconnected by low density radial spokes and wrapped by a three-start external winding. The unperturbed component of the map is strikingly similar to the known plain filament maps and, in particular, to that of Caulobacter crescentus. The helically perturbed component contributes mainly to the filaments's exterior (domain D3) where it comprises the tips of the outer domains interconnecting, pairwise, along the 11-start protofilaments and, again, laterally along the 6-start lines forming vertical and horizontal loops. Strong intersubunit connectivity occurs in the D2 shell and in the inner shell which is dominated by 3-start densities. The contribution of the complex component to the radial spokes seems negligible.
KW - Complex bacterial flagellar filament
KW - Electron microscopy
KW - Helical perturbations
KW - Rhizobium lupini H13-3
KW - Three-dimensional helical reconstruction
UR - http://www.scopus.com/inward/record.url?scp=0031707108&partnerID=8YFLogxK
U2 - 10.1006/jsbi.1998.4001
DO - 10.1006/jsbi.1998.4001
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AN - SCOPUS:0031707108
SN - 1047-8477
VL - 122
SP - 267
EP - 282
JO - Journal of Structural Biology
JF - Journal of Structural Biology
IS - 3
ER -