Crystal structure of the Mycoplasma arthritidis-derived mitogen in apo form reveals a 3D domain-swapped dimer.
Crystal structure of the Mycoplasma arthritidis-derived mitogen in apo form reveals a 3D domain-swapped dimer.
复制标题
关节炎支原体衍生的有丝分裂原的 apo 形式的晶体结构揭示了 3D 结构域交换二聚体。
DOI：
10.1016/j.jmb.2010.04.030
复制
发表时间：
2010
影响因子：
5.6
通讯作者：
Li,Hongmin
中科院分区：
文献类型：
--
作者：
Liu,Lihui;Li,Zhong;Guo,Yi;VanVranken,SandraJ;Mourad,Walid;Li,Hongmin
Mycoplasma arthritidis-derived mitogen (MAM) is a superantigen that can activate large fractions of T cells bearing particular Vβ elements of T cell receptor. Here, we report the crystal structure of a MAM mutant K201A in apo form (unliganded) at 2.8-Å resolutions. We also partially refined the crystal structures of the MAM wild type and another MAM mutant L50A in apo forms at low resolutions. Unexpectedly, the structures of these apo MAM molecules display a three-dimensional domain-swapped dimer. The entire C-terminal domains of these MAM molecules are involved in the domain swapping. Functional analyses demonstrated that the K201A and L50A mutants do not show altered ability to bind to their host receptors and that they stimulate the activation of T cells as efficiently as does the wild type. Structural comparisons indicated that the “reconstituted” MAM monomer from the domain-swapped dimer displays large differences at the hinge regions from the MAMwtmolecule in the receptor-bound form. Further comparison indicated that MAM has a flexible N-terminal loop, implying that conformational changes could occur upon receptor binding.
