Avian reovirus fibre, a homotrimer of the σC protein, is responsible for primary host-cell attachment. Using the protease trypsin, a C-terminal σC fragment containing amino acids 156–326 has been generated which was subsequently purified and crystallized. Two different crystal forms were obtained, one grown in the absence of divalent cations and belonging to space group P6322 (unit-cell parameters a = 75.6, c = 243.1 Å) and one grown in the presence of either zinc or cadmium sulfate and belonging to space group P321 (unit-cell parameters a = 74.7, c = 74.5 Å and a = 73.1, c = 69.9 Å for the ZnII- and CdII-grown crystals, respectively). The first crystal form diffracted synchrotron radiation to 3.0 Å resolution and the second form to 2.2–2.3 Å. Its closest related structure, the C-terminal fragment of mammalian reovirus fibre, has only 18% sequence identity and molecular-replacement attempts were unsuccessful. Therefore, a search is under way for suitable heavy-atom derivatives and attempts are being made to grow protein crystals containing selenomethionine instead of methionine.
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机译:禽呼肠孤病毒纤维(一种σC蛋白的同源三聚体)负责初级宿主细胞的附着。使用蛋白酶胰蛋白酶,已生成了包含氨基酸156-326的C端σC片段,随后将其纯化和结晶。获得了两种不同的晶体形式,一种在无二价阳离子的情况下生长,属于空间群P6322(晶胞参数a = 75.6,c = 243.1Å),一种在存在锌或硫酸镉的情况下生长,属于P321空间群(Zn II sup>-和Cd II sup>生长晶体的晶胞参数a = 74.7,c = 74.5Å和a = 73.1,c = 69.9Å , 分别)。第一种晶形将同步加速器辐射衍射到3.0Å的分辨率,第二种晶形将其衍射到2.2-2.3Å。其最接近的相关结构,即哺乳动物呼肠孤病毒纤维的C-末端片段,仅具有18%的序列同一性,并且分子置换尝试均未成功。因此,正在寻找合适的重原子衍生物,并且正在尝试生长含有硒代蛋氨酸而不是蛋氨酸的蛋白质晶体。
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