High-resolution crystal structure of an artificial (betaalpha)(8)-barrel protein designed from identical half-barrels.
High-resolution crystal structure of an artificial (betaalpha)(8)-barrel protein designed from identical half-barrels.
复制标题
由相同的半桶设计的人工 (betaalpha)(8) 桶蛋白的高分辨率晶体结构。
作者：
B. Höcker;A. Lochner;Tobias Seitz;Jörg Claren;R. Sterner
大量证据表明，普遍存在的（betaalpha）（8）-桶酶折叠是通过祖先（betaalpha）（4）-半桶酶的复制和融合而进化的。为了在实验室中用模型蛋白重建这一过程，我们早先融合了咪唑甘油磷酸合酶（HisF）的C-末端半桶HisF-C的两个拷贝，并逐步稳定得到的HisF-CC构建体。我们现在通过引入两个额外的氨基酸交换进一步增加了其稳定性和溶解性，这使得我们能够结晶所得的人工（β α）（8）-桶蛋白HisF-C *C。在2.1 A分辨率下对其X射线结构的分析揭示了与野生型HisF惊人的相似性，有助于我们理解其改善的稳定性，并为（betaalpha）（8）-桶蛋白的进化提供了进一步的见解。
Ample evidence suggests that the ubiquitous (betaalpha)(8)-barrel enzyme fold has evolved by the duplication and fusion of an ancestral (betaalpha)(4)-half-barrel. To reconstruct this process in the laboratory with a model protein, we earlier fused two copies of the C-terminal half-barrel HisF-C of imidazole glycerol phosphate synthase (HisF) and stepwise stabilized the resulting HisF-CC construct. We now further increased its stability and solubility by introducing two additional amino acid exchanges, which allowed us to crystallize the resulting artificial (betaalpha)(8)-barrel protein HisF-C***C. The analysis of its X-ray structure at 2.1 A resolution reveals a striking similarity to wild-type HisF, helps us to understand its improved stability, and provides further insights into the evolution of (betaalpha)(8)-barrel proteins.