Structural and biophysical analysis of nuclease protein antibiotics.
Structural and biophysical analysis of nuclease protein antibiotics.
复制标题
核酸酶蛋白抗生素的结构和生物物理分析。
DOI：
10.1042/bcj20160544
复制
发表时间：
2016-09-15
期刊：
影响因子：
--
通讯作者：
Kleanthous C
中科院分区：
文献类型：
--
作者：
Klein A;Wojdyla JA;Joshi A;Josts I;McCaughey LC;Housden NG;Kaminska R;Byron O;Walker D;Kleanthous C
蛋白质抗生素（细菌素）是一个庞大且多样化的多域毒素家族，可在种内资源竞争过程中杀死特定的革兰氏阴性细菌。近年来，我们对此类强效毒素输入机制的了解显着增加，特别是随着细菌素结构域的几种结构的报道。完整细菌素的结构生物化学以及它们如何在细菌物种之间进行比较还不太了解。在这里，我们重点关注靶向大肠杆菌和铜绿假单胞菌基因组的核酸内切酶 (DNase) 细菌素，分别称为 E 型大肠杆菌素和 S 型脓毒素，与其特异性免疫 (Im) 蛋白结合。首先，我们报道了 DNase 大肠杆菌素 ColE9 与其超高亲和力 Im 蛋白 Im9 复合物的 3.2 Å 结构。与 Im3 相比，当 Im3 与同源大肠菌素 ColE3 的核糖核酸酶结构域结合时，会与毒素的易位 (T) 结构域接触，我们发现 Im9 没有这种接触，仅观察到与 ColE9 细胞毒性结构域的相互作用。其次，我们报告了两种 S 型 DNase pyocins S2 和 AP41 的小角度 X 射线散射数据，其中安装了最近确定的隔离域的 X 射线结构。我们发现 DNase 脓毒素和大肠菌素都是高度伸长的分子，尽管它们的组成域的顺序不同。我们在蛋白质抗生素通过革兰氏阴性细菌细胞包膜的易位机制的背景下讨论了这些结构相似性和差异的含义。
Protein antibiotics (bacteriocins) are a large and diverse family of multidomain toxins that kill specific Gram-negative bacteria during intraspecies competition for resources. Our understanding of the mechanism of import of such potent toxins has increased significantly in recent years, especially with the reporting of several structures of bacteriocin domains. Less well understood is the structural biochemistry of intact bacteriocins and how these compare across bacterial species. Here, we focus on endonuclease (DNase) bacteriocins that target the genomes of Escherichia coli and Pseudomonas aeruginosa, known as E-type colicins and S-type pyocins, respectively, bound to their specific immunity (Im) proteins. First, we report the 3.2 Å structure of the DNase colicin ColE9 in complex with its ultra-high affinity Im protein, Im9. In contrast with Im3, which when bound to the ribonuclease domain of the homologous colicin ColE3 makes contact with the translocation (T) domain of the toxin, we find that Im9 makes no such contact and only interactions with the ColE9 cytotoxic domain are observed. Second, we report small-angle X-ray scattering data for two S-type DNase pyocins, S2 and AP41, into which are fitted recently determined X-ray structures for isolated domains. We find that DNase pyocins and colicins are both highly elongated molecules, even though the order of their constituent domains differs. We discuss the implications of these architectural similarities and differences in the context of the translocation mechanism of protein antibiotics through the cell envelope of Gram-negative bacteria.