Cameron Dale M, Thompson Jill, March Paul E, Dahlberg Albert E
School of Microbiology and Immunology, University of New South Wales, Sydney, NSW 2052, Australia.
J Mol Biol. 2002 May 24;319(1):27-35. doi: 10.1016/S0022-2836(02)00235-8.
The bacterial translational GTPases (initiation factor IF2, elongation factors EF-G and EF-Tu and release factor RF3) are involved in all stages of translation, and evidence indicates that they bind to overlapping sites on the ribosome, whereupon GTP hydrolysis is triggered. We provide evidence for a common ribosomal binding site for EF-G and IF2. IF2 prevents the binding of EF-G to the ribosome, as shown by Western blot analysis and fusidic acid-stabilized EF-G.GDP.ribosome complex formation. Additionally, IF2 inhibits EF-G-dependent GTP hydrolysis on 70 S ribosomes. The antibiotics thiostrepton and micrococcin, which bind to part of the EF-G binding site and interfere with the function of the factor, also affect the function of IF2. While thiostrepton is a strong inhibitor of EF-G-dependent GTP hydrolysis, GTP hydrolysis by IF2 is stimulated by the drug. Micrococcin stimulates GTP hydrolysis by both factors. We show directly that these drugs act by destabilizing the interaction of EF-G with the ribosome, and provide evidence that they have similar effects on IF2.
细菌翻译GTP酶（起始因子IF2、延伸因子EF - G和EF - Tu以及释放因子RF3）参与翻译的各个阶段，有证据表明它们与核糖体上的重叠位点结合，从而触发GTP水解。我们提供了EF - G和IF2存在共同核糖体结合位点的证据。如蛋白质印迹分析和夫西地酸稳定的EF - G.GDP.核糖体复合物形成所示，IF2可阻止EF - G与核糖体结合。此外，IF2抑制70S核糖体上EF - G依赖的GTP水解。与EF - G结合位点的一部分结合并干扰该因子功能的抗生素硫链丝菌素和小球霉素，也会影响IF2的功能。硫链丝菌素是EF - G依赖的GTP水解的强抑制剂，而该药物可刺激IF2介导的GTP水解。小球霉素可刺激这两种因子的GTP水解。我们直接表明这些药物通过破坏EF - G与核糖体的相互作用起作用，并提供证据表明它们对IF2有类似影响。
