Patterns in Nature—S-Layer Lattices of Bacterial and Archaeal Cells

Abstract

Bacterial surface layers (S-layers) have been observed as the outermost cell envelope component in a wide range of bacteria and most archaea. S-layers are monomolecular lattices composed of a single protein or glycoprotein species and have either oblique, square or hexagonal lattice symmetry with unit cell dimensions ranging from 3 to 30 nm. They are generally 5 to 10 nm thick (up to 70 nm in archaea) and represent highly porous protein lattices (30–70% porosity) with pores of uniform size and morphology in the range of 2 to 8 nm. Since S-layers can be considered as one of the simplest protein lattices found in nature and the constituent units are probably the most abundantly expressed proteins on earth, it seems justified to briefly review the different S-layer lattice types, the need for lattice imperfections and the discussion of S-layers from the perspective of an isoporous protein network in the ultrafiltration region. Finally, basic research on S-layers laid the foundation for applications in biotechnology, synthetic biology, and biomimetics.

The Polygonal Cell Shape and Surface Protein Layer of Anaerobic Methane-Oxidizing Methylomirabilislanthanidiphila Bacteria

“…Instead of adhering to the cell body as usually seen in other microorganisms ( van Teeseling et al, 2014 ; Bharat et al, 2017 ; Gambelli et al, 2019 ; Gaisin et al, 2020 ; von Kügelgen et al, 2020 ; Oatley et al, 2020 . For examples of reviews see Albers and Meyer (2011) ; Pavkov-Keller et al (2011) , Rodrigues-Oliveira et al (2017) , and Pum et al (2021) , the S-layer of M. lanthanidiphila formed several distinct patches. These patches had the appearance of planar sheets and intersected at sharp ridges, thereby likely defining the polygonal shape of the cell.…”

A Next-Generation qPlus-Sensor-Based AFM Setup: Resolving Archaeal S-Layer Protein Structures in Air and Liquid

“…Surface (S)-layers are highly ordered protein structures that surround many bacteria and form the cell wall in almost all archaea, as sketched in Figure a. − S-layers form a robust lattice structure, , working as protective membranes and shielding the cell from potentially extreme environmental conditions. In most cases, S-layer proteins form a monomolecular assembly of identical subunits and maintain their arrangement in two-dimensional (2D) structures even after isolation from cells .…”

“…In most cases, S-layer proteins form a monomolecular assembly of identical subunits and maintain their arrangement in two-dimensional (2D) structures even after isolation from cells . Lattices in oblique p1 and p2, square p4, or hexagonal p3 and p6 structures (p6 symmetry is depicted in Figure b) have been reported in the literature . Their robustness and the ability to self-assemble in vitro have made S-layers the focus of nanotechnological applications including filters, as building blocks, and patterning elements for further self-assembled structures. − …”

Dynamic Profile of S-Layer Proteins Controls Surface Properties of Emetic Bacillus cereus AH187 Strain

“…Numerous bacteria and almost all archaea are covered by a two-dimensional porous paracrystalline lattice. This 5–70 nm thick lattice is known as the Surface layer (S-layer; Bharat et al, 2021 ; Pum et al, 2021 ). The S-layer is composed of one or two extracellular 40-200-kDa (glyco)proteins ( Sára and Sleytr, 2000 ), called S-layer proteins (SLP), that self-assemble into a number of symmetries: oblique (p1 and p2), square (p4), and hexagonal (p3 and p6; Sleytr et al, 1999 ).…”