Crystal structure of the D85S mutant of bacteriorhodopsin: model of an O-like photocycle intermediate.
Crystal structure of the D85S mutant of bacteriorhodopsin: model of an O-like photocycle intermediate.
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DOI：
10.1006/jmbi.2001.5066
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发表时间：
2001-10
影响因子：
5.6
通讯作者：
S. Rouhani;Jean-Philippe Cartailler;M. Facciotti;P. Walian;R. Needleman;J. Lanyi;R. Glaeser;Hartmut Luecke
中科院分区：
文献类型：
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作者：
S. Rouhani;Jean-Philippe Cartailler;M. Facciotti;P. Walian;R. Needleman;J. Lanyi;R. Glaeser;Hartmut Luecke
报道了光驱动质子/羟基泵细菌视紫红质的D85 S和D85 S/F219 L突变体的晶体结构。这些突变体在正交C222（1）空间群中结晶，并首次证明基于单油酸甘油酯的立方脂质相结晶可以支持在非六方空间群中生长衍射良好的晶体。这两种结构表现出类似的和实质性的差异，相对于野生型细菌视紫红质，这表明它们代表固有的功能，从中和的席夫碱counterasp 85。我们认为，这些结构提供了一个模型的细菌视紫红质，其中Asp 85是质子化的，质子释放基团是去质子化的，和视网膜已重新异构化的全trans. Different为M和N光中间体，其中结构变化主要发生在细胞质侧，这里的大规模的变化仅限于细胞外侧的最后一个光循环中间体（O）。与M中间体一样，Arg 82的侧链呈向下构型，此外，在Trp 189 NE 1和Trp 138之间形成π-云氢键。在细胞质方面，有增加的水化附近的表面，这表明如何Asp 96可能与散装期间上升的O中间体。
Crystal structures are reported for the D85S and D85S/F219L mutants of the light-driven proton/hydroxyl-pump bacteriorhodopsin. These mutants crystallize in the orthorhombic C222(1) spacegroup, and provide the first demonstration that monoolein-based cubic lipid phase crystallization can support the growth of well-diffracting crystals in non-hexagonal spacegroups. Both structures exhibit similar and substantial differences relative to wild-type bacteriorhodopsin, suggesting that they represent inherent features resulting from neutralization of the Schiff base counterion Asp85. We argue that these structures provide a model for the last photocycle intermediate (O) of bacteriorhodopsin, in which Asp85 is protonated, the proton release group is deprotonated, and the retinal has reisomerized to all-trans. Unlike for the M and N photointermediates, where structural changes occur mainly on the cytoplasmic side, here the large-scale changes are confined to the extracellular side. As in the M intermediate, the side-chain of Arg82 is in a downward configuration, and in addition, a pi-cloud hydrogen bond forms between Trp189 NE1 and Trp138. On the cytoplasmic side, there is increased hydration near the surface, suggesting how Asp96 might communicate with the bulk during the rise of the O intermediate.