Brun E, Moriaud F, Gans P, Blackledge M J, Barras F, Marion D
Institut de Biologie Structurale "Jean-Pierre Ebel" (CEA-CNRS), 41 avenue des Martyrs, 38027 Grenoble Cedex, France.
Biochemistry. 1997 Dec 23;36(51):16074-86. doi: 10.1021/bi9718494.
Two-dimensional proton nuclear magnetic resonance spectroscopy has been used to determine the three-dimensional structure of the 62 amino acid C-terminal cellulose-binding domain (CBD) of the endoglucanase Z (CBDEGZ), secreted by Erwinia chrysanthemi. An experimental data set comprising 958 interproton nOe-derived restraints was used to calculate 23 structures. The calculated structures have an average root-mean-square deviation between Cys4 and Cys61 of 0.91 +/- 0.11 A for backbone atoms and 1.18 +/- 0.12 A for the heavy atoms. The CBDEGZ exhibits a skiboot shape based mainly on a triple antiparallel beta-sheet perpendicular to a less-ordered summital loop. Three aromatic rings (Trp18, Trp43, and Tyr44) are localized on one face of the protein and are exposed to the solvent in a conformation compatible with a cellulose-binding site. Based on its original folding, we have been able to relate the CBD sequence to those of several domains of unknown function occurring in several bacterial chitinases as well as other proteins. This study also provides a structural basis for analyzing the secretion-related information specific to the CBDEGZ.
二维质子核磁共振光谱已被用于确定由菊欧文氏菌分泌的内切葡聚糖酶Z（CBDEGZ）的62个氨基酸C末端纤维素结合结构域（CBD）的三维结构。一个包含958个质子间nOe衍生约束的实验数据集被用于计算23个结构。计算得到的结构中，Cys4和Cys61之间主链原子的平均均方根偏差为0.91±0.11 Å，重原子的平均均方根偏差为1.18±0.12 Å。CBDEGZ呈现滑雪靴形状，主要基于一个垂直于一个无序程度较低的顶点环的三重反平行β-折叠。三个芳香环（Trp18、Trp43和Tyr44）位于蛋白质的一个面上，并以与纤维素结合位点兼容的构象暴露于溶剂中。基于其原始折叠，我们能够将CBD序列与几种细菌几丁质酶以及其他蛋白质中出现的几个功能未知的结构域的序列联系起来。这项研究还为分析CBDEGZ特有的分泌相关信息提供了结构基础。
