The Escherichia coli rnlAB operon encodes a toxin-antitoxin module that is involved in protection against infection by bacteriophage T4. The full-length RnlA-RnlB toxin-antitoxin complex as well as the toxin RnlA were purified to homogeneity and crystallized. When the affinity tag is placed on RnlA, RnlB is largely lost during purification and the resulting crystals exclusively comprise RnlA. A homogeneous preparation of RnlA-RnlB containing stoichiometric amounts of both proteins could only be obtained using a His tag placed C-terminal to RnlB. Native mass spectrometry and SAXS indicate a 1:1 stoichiometry for this RnlA-RnlB complex. Crystals of the RnlA-RnlB complex belonged to space group C2, with unit-cell parameters a = 243.32, b = 133.58, c = 55.64 Å, β = 95.11°, and diffracted to 2.6 Å resolution. The presence of both proteins in the crystals was confirmed and the asymmetric unit is likely to contain a heterotetramer with RnlA2:RnlB2 stoichiometry.

中文翻译：

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大肠杆菌RnlA-RnlB毒素-抗毒素复合物：生产，表征和结晶。

大肠杆菌rnlAB操纵子编码一种毒素-抗毒素模块，该模块参与保护免受噬菌体T4的感染。将全长RnlA-RnlB毒素-抗毒素复合物以及毒素RnlA纯化至均质并结晶。当将亲和标签置于RnlA上时，RnlB在纯化过程中大量丢失，并且所得晶体仅包含RnlA。含有化学计量的两种蛋白质的RnlA-RnlB的均质制剂只能使用位于RnlB C端的His标签获得。天然质谱和SAXS表明该RnlA-RnlB复合物的化学计量比为1：1。RnlA-RnlB络合物的晶体属于C2空间群，其晶胞参数a = 243.32，b = 133.58，c = 55.64Å，β= 95.11°，并衍射至2.6Å分辨率。