The three‐dimensional structure of the regular surface protein of <i>Comamonas acidovorans</i> derived from native outer membranes and reconstituted two‐dimensional crystals

Journal of Structural Biology

2007

Many Archaea possess protein surface layers (S-layers) as the sole cell wall component. Slayers must therefore integrate the basic functions of mechanical and osmotic cell stabilisation. While the necessity is intuitively clear, the mechanism of structural osmoprotection by S-layers has not been elucidated yet. The theoretical analysis of a model Slayer-membrane assembly, derived from the typical cell envelope of Crenarchaeota, explains how S-layers impart lipid membranes with increased resistance to internal osmotic pressure and offers a quantitative assessment of S-layer stability. These considerations reveal the functional significance of S-layer symmetry and unit cell size and shed light on the rationale of S-layer architectures.

Section: Functional Impact Of the S-layer Unit Cell Sizementioning

confidence: 99%

Mechanism of osmoprotection by archaeal S-layers: A theoretical study

Journal of Structural Biology

2007

“…10 B. This mass presumably represents the domain pointing towards the membrane and mediating the tight contact as suggested from a three-dimensional reconstruction of the surface protein (30). This illustrates the excellent preservation of the structure of the surface protein attached to the DMPC membrane.…”

Section: Structure Of the Reconstituted Surface Proteinmentioning

confidence: 75%

“…We have used this approach to reconstitute the surface protein of the bacterium Comamonas acidovorans on DMPC vesicles. The protein is not a typical intrinsic membrane protein but is tightly associated with the outer membrane of the bacterial cell and is probably anchored to it by a small hydrophobic domain (29,30). Therefore, the surface protein can be treated like an intrinsic membrane protein in twodimensional crystallization experiments.…”

Section: Discussionmentioning

confidence: 99%

“…The morphological complexes have the same architecture in the native lattice and in reconstituted crystals and the unit cell dimensions are identical (lattice constant 10.5 nm). The morphological complex is a dimer (29,30) characterized by two units of mass. As indicated in Fig.…”

Section: Structure Of the Reconstituted Surface Proteinmentioning

confidence: 99%

“…The surface protein of the eubacterium Comamonas acidovorans which is investigated in this study belongs to group three or four of the above classification. We have applied various two-dimensional crystallization techniques to the surface protein to improve the quality and size of crystals for electron crystallography (29,30). To study the rather strong interaction of the surface protein with the underlying membrane and its consequences for the physico-chemical properties of the membrane, it is necessary to reconstitute the protein on synthetic lipid membranes.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Two-dimensional crystallization of a bacterial surface protein on lipid vesicles under controlled conditions

Paul

Jakubowski

et al. 1992

Biophysical Journal

Self Cite

The solubilized surface protein of the Gram-negative bacterium Comamonas acidovorans was reconstituted on lipid vesicles by means of controlled dialysis. To this end, a multichamber dialysis apparatus was built which allows one to control the temperature and the dialysis rate, to apply various temperatures or buffer systems and sample conditions in a single experiment, and to monitor the turbidity of the sample by means of light scattering. The reconstitution conditions were optimized such that the surface protein formed two-dimensional crystals suitable for electron crystallography. The recrystallized surface protein arrays gave a resolution of approximately 1.3 nm in projection after correlation averaging of negatively stained preparations. The surface protein assembled into partially self-contained two-dimensional crystals which possess a strong shape-determining effect and formed cylinders and various cone-shaped vesicles. The development of the various vesicle forms is described in a model.

S ‐Layers

Encyclopedia of Life Sciences

2016

Microbial surface layer (S‐layer) proteins assemble into two‐dimensional (2D) crystalline lattices on the cell surface of many species of Archaea and Bacteria and represent the outermost cell wall component, except for the existence of a carbohydrate capsule. Despite their widespread occurrence, the function of S‐layers remained obscure. Analysing the S‐layer structure on the one hand and the interaction of the 2D crystal with the underlying cell membrane on the other, reveals the S‐layers' cell wall function and the mechanism of cell stabilisation in Archaea . This basic function is not obvious in Bacteria . Here, experimental data suggest a major role in mediating and controlling interactions of S‐layers with the microbes' environment. The hybrid functional role of S‐layers will be understood more clearly if structural research is combined with the investigation of S‐layer interactions with the adjacent cell envelope components and the complex environmental factors. Key Concepts Microbial S‐layers have a hybrid functional role, that is, mediating cell stability and controlling cell surface properties. The architecture of S‐layers and their close interactions with the cell membrane determine and explain the S‐layers' cell wall function in Archaea . Attracting and repelling surface characteristics of S‐layers in Bacteria mediate the interactions with the environment and contribute to the proliferation and survival of cells. The investigation of S‐layer functions requires the combined analysis of the S‐layer structure and its impact on the cell envelope components as well as of interactions with environmental factors.