Sructural study of the M4 Immune Evasion Protein

溶液核磁共振是蛋白质和蛋白质复合物结构表征的有力工具，不超过200-300个氨基酸残基，但难以获得大量正确折叠的、同位素富集的蛋白质，这使得这种方法对m04蛋白具有挑战性。然而，我们已经能够获得该系统几乎完整的骨干共振分配以及有限的酰胺-酰胺NOE数据。利用罗塞塔程序的建模技术的最新进展，原则上使基于这种化学位移和有限的NOE信息对蛋白质结构进行建模成为可能。Rosetta隐含的物理上真实的能量函数可以区分原生和非原生蛋白质构象，化学位移和NOE信息大大减少了构象空间的允许区域。m04的精细模型已经从这种方法中衍生出来，揭示了一个与普通Igg折叠大致相似的结构，但有许多新的元素。基于序列同源性，该新结构可以代表m02-m06蛋白家族的所有成员。

Solution NMR is a powerful tool for structural characterization of proteins and protein complexes not exceeding 200-300 amino acid residues, but difficulties in obtaining large quantities of properly refolded, isotopically enriched protein make this approach challenging for the m04 protein. However, we have been able to obtain virtually complete backbone resonance assignments as well as limited amide-amide NOE data for this system. Recent advances in modeling techniques using the program Rosetta in principle make it possible to model the structure of the protein on the basis of this chemical shift and limited NOE information. The physically realistic energy function implicit to Rosetta can discriminate native from non-native protein conformations and the chemical shift and NOE information strongly reduce the permissible region of conformational space. Refined models for m04 have been derived from this approach, revealing a structure that is roughly similar to the common Igg fold, but with numerous novel elements. Based on sequence homology, the new structure is believed to be representative of all members of the m02-m06 protein family.