Messner P, Pum D, Sleytr U B
Zentrum für Ultrastrukturforschung, Universität für Bodenkultur, Wien, Austria.
J Ultrastruct Mol Struct Res. 1986 Oct-Dec;97(1-3):73-88. doi: 10.1016/s0889-1605(86)80008-8.
The ultrastructure of the crystalline surface layer (S-layer) of Bacillus stearothermophilus strain NRS 2004/3a has been characterized by electron microscopy supplemented by optical and computer image analysis. The S-layer, composed of glycoprotein subunits, has oblique symmetry, and can be extracted by guanidine hydrochloride. Upon dialysis, this extract produced both flat and cylindrical mono- and double-layer self-assembly products. Optical diffraction analysis of negatively stained preparations showed five types of double-layered assembly products. Computer filtering separated the double-layer complexes and revealed them to be composed of a common monolayer with p2-symmetry (a = 9.4 nm, b = 11.6 nm, and gamma = ca. 78 degrees). By analysis of freeze-dried and heavy metal-shadowed self-assemblies the surface topography and the characteristic "handedness" of the morphological units have been determined. Labeling with polycationic ferritin has shown that each surface of the S-layer possessed a different net charge. The results indicate that S-layers in vivo could prevent autoagglutination of cells.
嗜热脂肪芽孢杆菌菌株NRS 2004/3a的晶体表面层（S层）的超微结构已通过电子显微镜进行表征，并辅以光学和计算机图像分析。S层由糖蛋白亚基组成，具有斜对称结构，可通过盐酸胍提取。透析后，该提取物产生了扁平状和圆柱状的单层及双层自组装产物。对负染制剂的光学衍射分析显示了五种类型的双层组装产物。计算机过滤分离出双层复合物，并揭示它们由具有p2对称性（a = 9.4 nm，b = 11.6 nm，γ = 约78度）的共同单层组成。通过对冻干和重金属阴影自组装体的分析，确定了形态单元的表面形貌和特征“手性”。用聚阳离子铁蛋白标记表明S层的每个表面具有不同的净电荷。结果表明，体内的S层可以防止细胞的自凝集。
