Three-dimensional structure of the surface protein layer (MW layer) of Bacillus brevis 47.
The three-dimensional (3D) structure of one surface protein layer from Bacillus brevis 47, the middle wall (MW) layer, has been reconstructed from tilted-view electron micrographs after correlation averaging to a resolution of 2 nm. The MW layer has p6 symmetry with a center-to-center spacing of 18.3 nm and a minimum thickness of 5.5 nm. The reconstruction reveals a distinct domain structure: the heavier domain of six monomers jointly forms a massive core centered at the sixfold symmetry axis, and lighter domains interconnect adjacent unit cells. In addition, the larger domains collectively form a pore by making contact with each other towards the inner surface, while the smaller domains establish a second connectivity towards the outer surface of the S layer. The MW layer of B. brevis resembles the S layer of Acetogenium kivui in various aspects: they have very similar lattice parameters and highly reminiscent 3D structures; the pores penetrate through the whole core and appear to determine the porosity of the S layers.
Tsuboi
A
A
Max-Planck-Institut für Biochemie, Martinsried, Federal Republic of Germany.
Engelhardt
H
H
Santarius
U
U
Tsukagoshi
N
N
Udaka
S
S
Baumeister
W
W
D001407:Bacillus / Q000648:ultrastructure*; D002462:Cell Membrane / Q000648:ultrastructure; D008854:Microscopy, Electron