Architecture and modular assembly of Sulfolobus S-layers revealed by electron cryotomography

Proc Natl Acad Sci U S A. 2019 Dec 10;116(50):25278-25286. doi: 10.1073/pnas.1911262116. Epub 2019 Nov 25.


Surface protein layers (S-layers) often form the only structural component of the archaeal cell wall and are therefore important for cell survival. S-layers have a plethora of cellular functions including maintenance of cell shape, osmotic, and mechanical stability, the formation of a semipermeable protective barrier around the cell, and cell-cell interaction, as well as surface adhesion. Despite the central importance of S-layers for archaeal life, their 3-dimensional (3D) architecture is still poorly understood. Here we present detailed 3D electron cryomicroscopy maps of archaeal S-layers from 3 different Sulfolobus strains. We were able to pinpoint the positions and determine the structure of the 2 subunits SlaA and SlaB. We also present a model describing the assembly of the mature S-layer.

Keywords: S-layers; Sulfolobus; archaea; electron cryotomography; subtomogram averaging.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cryoelectron Microscopy
  • Dimerization
  • Membrane Glycoproteins / chemistry
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Membrane Glycoproteins / ultrastructure*
  • Sulfolobus / chemistry
  • Sulfolobus / genetics
  • Sulfolobus / metabolism*
  • Sulfolobus / ultrastructure


  • Membrane Glycoproteins
  • S-layer proteins