Ve Thomas, Williams Simon, Valkov Eugene, Ellis Jeffrey G, Dodds Peter N, Kobe Bostjan
School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience (Division of Chemistry and Structural Biology), University of Queensland, Brisbane, QLD, Australia.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2011 Feb 1;67(Pt 2):237-40. doi: 10.1107/S1744309110051006. Epub 2011 Jan 22.
The Toll/interleukin-1 receptor (TIR) domain is a protein-protein interaction domain that is found in both animal and plant immune receptors. In animal Toll-like receptor signalling, both homotypic TIR-domain interactions between two receptor molecules and heterotypic interactions between receptors and TIR-domain-containing adaptors are required for initiation of an innate immune response. The TIR domains in cytoplasmic nucleotide-binding/leucine-rich repeat (NB-LRR) plant disease-resistance proteins are not as well characterized, but recent studies have suggested a role in defence signalling. In this study, the crystallization, X-ray diffraction analysis and preliminary structure determination of the TIR domain from the flax resistance protein L6 (L6TIR) are reported. Plate-like crystals of L6TIR were obtained using PEG 200 as a precipitant and diffracted X-rays to 2.3 Å resolution. Pseudo-translation complicated the initial assignment of the crystal symmetry, which was ultimately found to correspond to space group P2(1)2(1)2 with two molecules per asymmetric unit. The structure of L6TIR was solved by molecular replacement using the structure of the TIR-domain-containing protein AT1G72930 from Arabidopsis as a template.
Toll/白细胞介素-1受体（TIR）结构域是一种蛋白质-蛋白质相互作用结构域，存在于动物和植物免疫受体中。在动物Toll样受体信号传导中，两个受体分子之间的同型TIR结构域相互作用以及受体与含TIR结构域的衔接蛋白之间的异型相互作用都是启动先天免疫反应所必需的。细胞质核苷酸结合/富含亮氨酸重复序列（NB-LRR）植物抗病蛋白中的TIR结构域尚未得到充分表征，但最近的研究表明其在防御信号传导中发挥作用。在本研究中，报道了亚麻抗性蛋白L6的TIR结构域（L6TIR）的结晶、X射线衍射分析和初步结构测定。使用PEG 200作为沉淀剂获得了L6TIR的板状晶体，其X射线衍射分辨率达到2.3 Å。伪平移使晶体对称性的初始归属变得复杂，最终发现其对应于空间群P2(1)2(1)2，每个不对称单元中有两个分子。通过以拟南芥含TIR结构域的蛋白AT1G72930的结构为模板进行分子置换，解析了L6TIR的结构。
