Engelhardt H, Saxton W O, Baumeister W
J Bacteriol. 1986 Oct;168(1):309-17. doi: 10.1128/jb.168.1.309-317.1986.
The three-dimensional structure of the regular surface layer of Sporosarcina ureae has been determined to a resolution of 1.7 nm by electron microscopy and image reconstruction. The S-layer has p4 symmetry, a lattice constant of 12.9 nm, and a minimum thickness of 6.6 nm. The reconstruction reveals a distinct domain structure: a massive core, arms connecting adjacent unit cells, and spurs which make contact at the subsidiary fourfold symmetry axes. In the z-direction the domains appear to be arranged in three planes, creating two entirely different surface reliefs. The S-layer has a complex pattern of pores and gaps that are 2 to 3 nm wide. In addition, the secondary-structure composition has been determined by infrared spectroscopy: about 35% of the polypeptide appears to have a beta-structure conformation.
通过电子显微镜和图像重建技术，已确定了脲芽孢八叠球菌规则表面层的三维结构，分辨率达到1.7纳米。S层具有p4对称性，晶格常数为12.9纳米，最小厚度为6.6纳米。重建结果显示出一种独特的结构域结构：一个厚实的核心、连接相邻晶胞的臂以及在辅助四重对称轴处接触的刺。在z方向上，这些结构域似乎排列在三个平面中，形成了两种完全不同的表面起伏。S层具有复杂的孔隙和间隙模式，宽度为2至3纳米。此外，通过红外光谱法确定了二级结构组成：约35%的多肽似乎具有β结构构象。
