Structural Basis for Substrate Recognition in the Enzymatic Component of ADP-ribosyltransferase Toxin CDTa from Clostridium difficile
Structural Basis for Substrate Recognition in the Enzymatic Component of ADP-ribosyltransferase Toxin CDTa from Clostridium difficile
复制标题
艰难梭菌 ADP-核糖基转移酶毒素 CDTa 酶成分底物识别的结构基础
DOI：
--
复制
发表时间：
2009
影响因子：
4.8
通讯作者：
K. Acharya
中科院分区：
文献类型：
--
作者：
A. Sundriyal;A. Roberts;C. Shone;K. Acharya
ADP-核糖基化是几种细菌采用的细胞中毒的有利模式之一。艰难梭菌被认为是一种重要的医院病原体与相当大的发病率和归因死亡率。沿着其两种众所周知的毒素，毒素A和毒素B，其产生靶向靶细胞的单体肌动蛋白的ADP-核糖基化毒素。与其他梭菌肌动蛋白ADP核糖基化毒素一样，这种二元毒素被称为C。艰难梭菌毒素（CDT）由CDTa和CDTb两个亚基组成。在这项研究中，我们提出了高分辨率的晶体结构的CDTa在其天然形式（在pH 4.0，8.5，和9.0），并在复杂的ADP-核糖捐助者，NAD和NADPH（在pH 9.0）。天然蛋白质的晶体结构显示出局限于蛋白质的活性位点区域的“显著的构象灵活性”和在低pH下的“增强的”紊乱，而复杂结构突出了与密切同源物产气荚膜梭菌i毒素的酶亚基相比“配体特异性”的显著差异。特别是在CDTa中，两个建议的催化重要残基（Glu-385和Glu-387）似乎在配体结合中不起作用或不太重要。这些结构数据提供了关于CDTa中蛋白质-供体底物复合物稳定化的第一个详细信息，这可能对理解CDT识别具有影响。
ADP-ribosylation is one of the favored modes of cell intoxication employed by several bacteria. Clostridium difficile is recognized to be an important nosocomial pathogen associated with considerable morbidity and attributable mortality. Along with its two well known toxins, Toxin A and Toxin B, it produces an ADP-ribosylating toxin that targets monomeric actin of the target cell. Like other Clostridial actin ADP-ribosylating toxins, this binary toxin, known as C. difficile toxin (CDT), is composed of two subunits, CDTa and CDTb. In this study, we present high resolution crystal structures of CDTa in its native form (at pH 4.0, 8.5, and 9.0) and in complex with ADP-ribose donors, NAD and NADPH (at pH 9.0). The crystal structures of the native protein show “pronounced conformational flexibility” confined to the active site region of the protein and “enhanced” disorder at low pH, whereas the complex structures highlight significant differences in “ligand specificity” compared with the enzymatic subunit of a close homologue, Clostridium perfringens iota toxin. Specifically in CDTa, two of the suggested catalytically important residues (Glu-385 and Glu-387) seem to play no role or a less important role in ligand binding. These structural data provide the first detailed information on protein-donor substrate complex stabilization in CDTa, which may have implications in understanding CDT recognition.
C1 型和 C2 型肉毒梭菌毒素的药理学特性比较。
DOI：
--
发表时间：
1982
期刊：
The Journal of pharmacology and experimental therapeutics
影响因子：
--
作者：
Simpson,LL
通讯作者：
Simpson,LL