Structure of the isolated catalytic domain of diphtheria toxin.
Structure of the isolated catalytic domain of diphtheria toxin.
复制标题
白喉毒素分离催化结构域的结构。
DOI：
10.1021/bi00003a010
复制
发表时间：
1995
期刊：
影响因子：
2.9
通讯作者：
Eisenberg,D
中科院分区：
文献类型：
--
作者：
Weiss,MS;Blanke,SR;Collier,RJ;Eisenberg,D
1994年10月27日收到的修订稿件摘要：用2.5A分辨率的X射线结晶学测定了分离的白喉毒素催化结构域的结构，其R因子为19.7%。该结构域与其内源性抑制剂腺苷(3‘-*5，)尿苷3’-单磷酸(ApUp)结合。这个190个残基的结构域在大肠杆菌中表达并从大肠杆菌中分离出来，其结构与在pH 7.5下测定的整个白喉毒素的催化结构域的结构基本相同。然而，有两个相邻的表面环(环66-78和环169-176)与整个白喉毒素的催化结构域的结构相比显示出明显的差异。虽然这两个环都在蛋白质的表面，并且相对灵活，但链轨迹在电子密度中定义得很清楚。主要的结构差异是66-78环路和169-176环路的接近。我们将这种结构变化主要归因于与完整的白喉毒素相比，分离的催化域中没有相邻的跨膜结构域。我们认为，这一变化代表了白喉毒素结构域从催化结构域向移位结构域转变的第一步。详细描述了这些变化，并讨论了它们对膜转位的影响。
Revised Manuscript Received October 27, 1994s abstract: The structure of the isolated catalytic domain of diphtheria toxin at pH 5.0 was determined by X-ray crystallography at 2.5 A resolution and refined to an R-factor of 19.7%. The domain is bound to its endogenous inhibitor adenylyl (3'—* 5,) uridine 3'-monophosphate (ApUp). The structure of this 190-residue domain, which was expressed in and isolatedfrom Escherichia coli, is essentially identical to the structure of the catalytic domain within whole diphtheria toxin determined at pH 7.5. However, there are two adjacent surface loops (loop 66—78 and loop 169—176) thatexhibit clear differences when compared to the structure of the catalytic domain in whole diphtheria toxin. Although both loops are at the surface of the protein and are relatively flexible, the chain trace is well-defined in the electron density. The main structural difference is the closer approach of loops 66—78 and 169—176. We ascribe this structural change mainly to the absence of the neighboring transmembrane domain in the isolated catalytic domain as compared to whole diphtheria toxin. We suggest that this change represents the first step of the structural transition from the catalytic domainin whole diphtheria toxin to the translocated form of the domain. The changes are described in detail, and their implications for membrane translocation are discussed.