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

我们确定了a T细胞受体（TCR）B链的结构 与超抗原葡萄球菌肠毒素B（SE B）复合， 2.4
分辨率 我们还确定了结构，2.6
TCR B链和SE B突变体之间的复合物的解析 其中26位的缬氨酸被酪氨酸替代（SEB V26 Y）。 晶体属于空间群P21，晶胞尺寸a = 71.2
，B = 83.6
，c = 83.0
对于野生型b-SEB复合物，a = 70.9
，B = 83.0
，c = 82.8
突变体b-SEB V26 Y复合物的研究。 那里 是不对称单元中的两个复杂分子。 x射线衍射 数据高达2.4
（b-SEB）和2.6
（b-SEB V26 Y）在100 ℃下收集 oK来自使用同步加速器的每个复合物的一个闪速冷却晶体 用普林斯顿2K CCD检测器在CHESS光束线F-1处进行辐射。 的 将晶体浸泡在10%PEG 8000、24%甘油和0.1M Tris-HCl，pH 8.5，然后在液氮中快速冷却。 数据 使用HKL/DENZO/SCALEPACK进行整合和合并， 34，943个独特的反射，对于b-SEB，Rmerge= 9.2%， 对于b-SEB V26 Y，Rmerge= 8.1%的独特反射。 数据集 完成91.5%至2.4
对于b-SEB（79.1%从2.5-2.4
）和97.0% 完成2.6
对于b-SEB V26 Y（90.6%，从2.7-2.6
). 的 野生型b-SEB复合物的结构通过分子生物学方法解决。 用AMoRe程序（Navaza，1994）替换方法。 搜索 模型由14.3 d TCR B链组成，在1.7
决议 (PDB登录号1bec）和SEB细化为1.9
分辨率（PDB 登录号1 SE 4）。 结构通过迭代循环进行细化 模拟退火和温度因子（B）细化， X-PLOR与Fo-Fc和2Fo-Fc中的模型构建穿插 电子密度图使用TURBO-FROD。 最终模型包含 7，589个蛋白质原子和179个水分子，Rfree= 0.309， Rwork= 0.228，范围6-2.4
.均方根理想偏差 键长和键角为0.006
和1.79o。 的 开始测定b-SEB V26 Y突变体复合物的结构 来自b-SEB野生型复合物的部分精制结构。 b-SEB V26 Y复合物的最终模型包含6，915个蛋白质原子 在Rfree= 0.326和Rwork= 0.229的范围内， 6-2.6
.均方根偏离理想键长和键角 0.008
和1.37o。

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.