CRYSTAL STRUCTURE OF T CELL RECEPTOR B CHAIN BOUND TO SUPER ANTIGEN

我们测定了a T细胞受体(TCR)b链的结构 与超抗原葡萄球菌肠毒素B(SEB)络合 2.4决议。我们还确定了结构，为2.6 TCRb链与SEB突变体之间的复合体的拆分 其中26位的缬氨酸被酪氨酸取代(SEB V26Y)。 晶体属P21空间群，晶胞尺寸a=71.2 ，b=83.6，c=83.0对于野生型b-SEB络合物和a=70.9 ，b=83.0，c=82.8对于突变的b-SEB V26Y复合体。那里 是不对称单元中的两个复杂分子。X射线衍射法 最多2.4个数据(B-SEB)和2.6(B-SEB V26Y)以100 使用同步加速器为每个复合体提供一个闪冷晶体 用普林斯顿2K电荷耦合器件探测国际象棋光束线F-1的辐射。这个 晶体浸泡在10%聚乙二醇8000、24%甘油和0.1M中 Tris-HCl，pH 8.5，在液氮闪冷之前。数据 使用HKL/Denzo/SCALEPACK进行整合和合并 34,943次独特反射，b-SEB的Rmerge=9.2%，28,757次 B-SEB V26Y的Rmerge=8.1%的独特反射。数据集 是否已完成91.5%至2.4B-SEB(从2.5%到2.4%))和97.0% 完成到2.6对于b-SEB V26Y(从2.7到2.6的90.6%)。这个 用该分子解析了野生型b-SEB复合体的结构 用Amore程序替换方法(Navaza，1994)。搜索 模型由14.3d的TCR b链组成，精确度为1.7决议 (PDB加入代码1BEC)和SEB细化为1.9分辨率(PDB 注册代码1SE4)。该结构通过迭代循环进行了改进 模拟退火法和温度系数(B)的精化 X-PLOR穿插模型构建为Fo-FC和2Fo-FC 使用Turbo-Frod的电子密度图。最终的模型包含 7,589个蛋白质原子和179个水分子，RFree=0.309和 Rwork=0.228，范围为6-2.4.。火箭队。偏离理想 键长和键角为0.006和1.79度。这个 B-SEB V26Y突变体复合体的结构测定开始 来自b-SEB野生型复合体的部分精炼结构。 B-SEB V26Y复合体的最终模型包含6915个蛋白质原子 和31个水分子，其中RFree=0.326，Rwork=0.229 6-2.6。火箭队。与理想键长和键角的偏差 是0.008和1.37度。

We determined the structure of the a T cell receptor (TCR) b chain complexed with the superantigen staphylococcal enterotoxin B (SEB) to 2.4
resolution. We also determined the structure, to 2.6
resolution, of the complex between the TCR b chain and a mutant of SEB in which valine at position 26 is replaced by tyrosine (SEB V26Y). The crystals belong to space group P21 with cell dimensions a = 71.2
, b = 83.6
, c = 83.0
for the wild type b-SEB complex and a = 70.9
, b = 83.0
, c = 82.8
for the mutant b-SEB V26Y complex. There are two complex molecules in the asymmetric unit. X-ray diffraction data up to 2.4
(b-SEB) and 2.6
(b-SEB V26Y) were collected at 100 oK from one flash-cooled crystal for each complex using synchrotron radiation at CHESS beamline F-1 with a Princeton 2K CCD detector. The crystals were soaked in 10% PEG 8000, 24% glycerol, and 0.1 M Tris-HCl, pH 8.5, prior to flash-cooling in liquid nitrogen. Data were integrated and merged using HKL/DENZO/SCALEPACK which gives 34,943 unique reflections with Rmerge= 9.2% for b-SEB and 28,757 unique reflections with Rmerge= 8.1% for b-SEB V26Y. The data sets are 91.5% complete to 2.4
for b-SEB (79.1% from 2.5-2.4
) and 97.0% complete to 2.6
for b-SEB V26Y (90.6% from 2.7-2.6
). The structure of the wild type b-SEB complex was solved by the molecular replacement method with the program AMoRe (Navaza, 1994). The search models consisted of the 14.3.d TCR b chain refined at 1.7
resolution (PDB accession code 1bec) and SEB refined at 1.9
resolution (PDB accession code 1SE4). The structure was refined by iterative cycles of simulated annealing and temperature factor (B) refinement using X-PLOR interspersed with model building into Fo- Fc and 2Fo- Fc electron density maps using TURBO-FROD. The final model contains 7,589 protein atoms and 179 water molecule with Rfree= 0.309 and Rwork= 0.228 in the range 6-2.4
. The r.m.s. deviations from ideal bond lengths and bond angles are 0.006
and 1.79o, respectively. The structure determination of the b-SEB V26Y mutant complex was begun from the partially refined structure of the b-SEB wild type complex. The final model of the b-SEB V26Y complex contains 6,915 protein atoms and 31 water molecule with Rfree= 0.326 and Rwork= 0.229 in the range 6-2.6
. The r.m.s. deviations from ideal bond lengths and bond angles are 0.008
and 1.37o, respectively.