title: The structure and binding behavior of the bacterial cell surface layer protein SbsC.
abstract: Surface layers (S-layers) comprise the outermost cell envelope component of most archaea and many bacteria. Here we present the structure of the bacterial S-layer protein SbsC from Geobacillus stearothermophilus, showing a very elongated and flexible molecule, with strong and specific binding to the secondary cell wall polymer (SCWP). The crystal structure of rSbsC((31-844)) revealed a novel fold, consisting of six separate domains, which are connected by short flexible linkers. The N-terminal domain exhibits positively charged residues regularly spaced along the putative ligand binding site matching the distance of the negative charges on the extended SCWP. Upon SCWP binding, a considerable stabilization of the N-terminal domain occurs. These findings provide insight into the processes of S-layer attachment to the underlying cell wall and self-assembly, and also accommodate the observed mechanical strength, the polarity of the S-layer, and the pronounced requirement for surface flexibility inherent to cell growth and division.
authors.affiliation: Institute of Molecular Biosciences, Structural Biology, University of Graz, Humboldtsrasse 50/3, 8010 Graz, Austria.
authors.forename: Tea
authors.initials: T
authors.lastname: Pavkov
authors.forename: Eva M
authors.initials: EM
authors.lastname: Egelseer
authors.forename: Manfred
authors.initials: M
authors.lastname: Tesarz
authors.forename: Dmitri I
authors.initials: DI
authors.lastname: Svergun
authors.forename: Uwe B
authors.initials: UB
authors.lastname: Sleytr
authors.forename: Walter
authors.initials: W
authors.lastname: Keller
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D001411:Geobacillus stearothermophilus / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins