Salama-Alber Orly, Gat Yair, Lamed Raphael, Shimon Linda J W, Bayer Edward A, Frolow Felix
Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2012 Sep 1;68(Pt 9):1116-9. doi: 10.1107/S1744309112033088. Epub 2012 Aug 31.
In Ruminococcus flavefaciens, a predominant fibre-degrading bacterium found in ruminants, cellulosomal proteins are anchored to the bacterial cell wall through a relatively small ScaE scaffoldin which includes a single type III cohesin. The cotton-binding protein CttA consists of two cellulose-binding modules and a C-terminal modular pair (XDoc) comprising an X-module and a contiguous dockerin, which exhibits high affinity towards the ScaE cohesin. Seleno-L-methionine-labelled derivatives of the ScaE cohesin module and the XDoc from CttA have been expressed, copurified and cocrystallized. The crystals belonged to the tetragonal space group P4(3)2(1)2, with unit-cell parameters a = b = 78.7, c = 203.4 Å, and the unit cell contains a single cohesin-XDoc complex in the asymmetric unit. The diffraction data were phased to 2.0 Å resolution using the anomalous signal of the Se atoms.
在黄化瘤胃球菌（一种在反刍动物中发现的主要纤维降解细菌）中，纤维小体蛋白通过相对较小的ScaE支架蛋白锚定在细菌细胞壁上，该支架蛋白包含单一的III型粘着蛋白。棉花结合蛋白CttA由两个纤维素结合模块和一个C端模块对（XDoc）组成，该模块对包括一个X模块和一个相邻的dockerin，它对ScaE粘着蛋白具有高亲和力。已表达、共纯化并共结晶了来自CttA的ScaE粘着蛋白模块和XDoc的硒代-L-甲硫氨酸标记衍生物。晶体属于四方晶系空间群P4(3)2(1)2，晶胞参数a = b = 78.7，c = 203.4 Å，且不对称单元中的晶胞包含一个单一的粘着蛋白-XDoc复合物。利用硒原子的异常信号，将衍射数据解析到2.0 Å分辨率。
