Zarivach Raz, Ben-Zeev Efrat, Wu Nan, Auerbach Tamar, Bashan Anat, Jakes Karen, Dickman Katherine, Kosmidis Alexander, Schluenzen Frank, Yonath Ada, Eisenstein Miriam, Shoham Menachem
Weizmann Institute of Science, Department of Structural Biology, Rehovot 76100, Israel.
Biochimie. 2002 May-Jun;84(5-6):447-54. doi: 10.1016/s0300-9084(02)01449-9.
Colicin E3 is a protein that kills Escherichia coli cells by a process that involves binding to a surface receptor, entering the cell and inactivating its protein biosynthetic machinery. Colicin E3 kills cells by a catalytic mechanism of a specific ribonucleolytic cleavage in 16S rRNA at the ribosomal decoding A-site between A1493 and G1494 (E. coli numbering system). The breaking of this single phosphodiester bond results in a complete cessation of protein biosynthesis and cell death. The inactive E517Q mutant of the catalytic domain of colicin E3 binds to 30S ribosomal subunits of Thermus thermophilus, as demonstrated by an immunoblotting assay. A model structure of the complex of the ribosomal subunit 30S and colicin E3, obtained via docking, explains the role of the catalytic residues, suggests a catalytic mechanism and provides insight into the specificity of the reaction. Furthermore, the model structure suggests that the inhibitory action of bound immunity is due to charge repulsion of this acidic protein by the negatively charged rRNA backbone
大肠杆菌素E3是一种蛋白质，它通过与表面受体结合、进入细胞并使其蛋白质生物合成机制失活的过程来杀死大肠杆菌细胞。大肠杆菌素E3通过在核糖体解码A位点（在A1493和G1494之间，大肠杆菌编号系统）对16S rRNA进行特异性核糖核酸裂解的催化机制来杀死细胞。这个单一磷酸二酯键的断裂导致蛋白质生物合成完全停止和细胞死亡。如免疫印迹分析所示，大肠杆菌素E3催化结构域的无活性E517Q突变体与嗜热栖热菌的30S核糖体亚基结合。通过对接获得的30S核糖体亚基与大肠杆菌素E3复合物的模型结构解释了催化残基的作用，提出了一种催化机制，并深入了解了反应的特异性。此外，模型结构表明，结合免疫的抑制作用是由于这种酸性蛋白质与带负电荷的rRNA主链之间的电荷排斥。
