Datta A B, Chakrabarti P, Subramanya H S, Parrack P
Department of Biochemistry, Bose Institute, P-1/12 CIT Scheme VIIM, Kolkata, 700054, India.
Biochem Biophys Res Commun. 2001 Nov 9;288(4):997-1000. doi: 10.1006/bbrc.2001.5880.
The CII protein of the temperate bacteriophage lambda is a transcriptional activator involved in the lysis-lysogeny switch of the phage. It is an unstable protein of 97 amino acids and is known to exist as a tetramer in the native state. The cII gene has been cloned and expressed in Escherichia coli using a T7 promoter based over-expression system. The recombinant CII protein has been purified to homogeneity by ammonium sulfate fractionation followed by two steps of ion-exchange chromatography. The purified protein crystallized at pH 8.2 in hanging-drop vapor diffusion method at 293 K. The crystals diffract to a resolution of 2.8 A and belong to the space group C222 with unit-cell parameters a = 64.10, b = 106.95 and c = 120.16 A.
温和噬菌体λ的CII蛋白是一种参与噬菌体裂解-溶原性转换的转录激活因子。它是一种由97个氨基酸组成的不稳定蛋白，已知在天然状态下以四聚体形式存在。利用基于T7启动子的过表达系统，已将cII基因克隆并在大肠杆菌中表达。重组CII蛋白经硫酸铵分级分离，然后经过两步离子交换色谱法纯化至同质。纯化后的蛋白在293 K下采用悬滴气相扩散法在pH 8.2条件下结晶。晶体衍射分辨率为2.8 Å，属于空间群C222，晶胞参数a = 64.10、b = 106.95和c = 120.16 Å。
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