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Publications

Journal Article Ppublish

PubMed: 42637081 DOI: 10.1016/j.jbc.2026.113461

Self-assembly of surface layer protein SbsC from Geobacillus stearothermophilus and common principles of Bacilli S-layers.

J Biol Chem 302(10):113461

Authors: Christoph Grininger, Lavinia Gambelli, Anđela Đordić, Markus Eder, Christoph Buhlheller, Theo Sagmeister, Gustav Oberdorfer, Janet Vonck, Uwe B Sleytr, Walter Keller, Bertram Daum, Tea Pavkov-Keller

Affiliations

  • Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria.
  • Living Systems Institute, University of Exeter, Exeter, United Kingdom; Library Services Research Support, University of Bristol, Bristol, United Kingdom.
  • Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria.
  • Institute of Biochemistry, University of Technology, Graz, Austria; BioTechMed-Graz, Graz, Austria.
  • Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
  • Institute of Synthetic Bioarchitectures, University of Natural Resources and Life Sciences Vienna, Vienna, Austria.
  • Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria; BioHealth, Field of Excellence BioHealth - University of Graz, Graz, Austria.
  • Living Systems Institute, University of Exeter, Exeter, United Kingdom.
  • Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria; BioHealth, Field of Excellence BioHealth - University of Graz, Graz, Austria.

Abstract

S-layers are (glyco)protein coats displayed on the external surface of many bacterial and archaeal species. By combining X-ray crystallography, electron cryo-tomography and SymProFold predictions, we propose the structure of the self-assembled S-layer protein (SLP) SbsC from the Gram-positive bacterium Geobacillus stearothermophilus ATCC 12980. SbsC consists of nine domains arranged like beads on a string. Domains 2 through 7 form a closed ring-like conformation, while the secondary cell wall polymer binding domain 1 and the auxiliary domains 8 and 9 protrude from the ring. Within the assembled lattice, the molecules adopt p1 symmetry and conform to the curvature of the bacterial surface, creating a sub-S-layer space, an enclosed space between the peptidoglycan layer and SLP lattice that may accommodate additional surface-associated proteins. Four Ca 2+ ions stabilize loop regions essential for intermolecular interactions and lattice integrity, while their removal reduces overall stability it does not abolish assembly. Comparative analysis with related SLPs, including SbsB from G. stearothermophilus and Sap/EA1 from Bacillus anthracis, supports a conserved ring-like domain arrangement across Bacillus-type S-layers. Given the involvement of S-layers in host interactions, immune evasion, and pathogenicity, particularly in Bacillusanthracis and Bacillus cereus group species, the identified intermolecular interfaces represent attractive targets for the development of novel antibacterial strategies.

MeSH

Biochemistry, Geobacillus, Gram-Positive Bacteria, Geobacillus Stearothermophilus