EF-G

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EF-G延伸因子G(英语:elongation factor G)的缩写,是原核延伸因子中的转位酶

目录

功能

The factor EF-G catalyzes the translocation of the tRNA and mRNA down the ribosome at the end of each round of polypeptide elongation. Homologous to EF-Tu + tRNA, EF-G also binds to the ribosome in its GTP-bound state. When it associates with the A site, EF-G causes the tRNA previously occupying that site to occupy an intermediate A/P position (bound to the A site of the small ribosomal subunit and to the P site of the large subunit), and the tRNA in the P site is shifted to a P/E hybrid state. EF-G hydrolysis of GTP causes a conformation change that forces the A/P tRNA to fully occupy the P site, the P/E tRNA to fully occupy the E site (and exit the ribosome complex), and the mRNA to shift three nucleotides down relative to the ribosome due to its association with these tRNA molecules. The GDP-bound EF-G molecule then dissociates from the complex, leaving another free A-site where the elongation cycle can start again.

除了在翻译中的作用外,EF-G还与核糖体再循环因子一起以GTP依赖方式促进核糖体再循环[1]

进化

EF-G有一个复杂的进化史,现代细菌基因组中存在的大量该延伸因子的旁系同源基因暗示了不同的EF-G变体可能在进化过程中发生了亚功能化[2]

临床意义

EF-G可被夫西地酸抑制,但有细菌也出现了耐药性[3][4]

参考文献

  1. Zavialov AV, Hauryliuk VV, Ehrenberg M.. Splitting of the posttermination ribosome into subunits by the concerted action of RRF and EF-G. Molecular Cell. 2005, 18 (6): 675–686. doi:10.1016/j.molcel.2005.05.016. PMID 15949442. 
  2. G C Atkinson, S L Baldauf. Evolution of elongation factor G and the origins of mitochondrial and chloroplast forms. Molecular Biology and Evolution. 2011, 28 (3): 1281–92. doi:10.1093/molbev/msq316. PMID 21097998. 
  3. Macvanin M, Hughes D. Hyper-susceptibility of a fusidic acid-resistant mutant of Salmonella to different classes of antibiotics. FEMS microbiology letters. June 2005, 247 (2): 215–20. doi:10.1016/j.femsle.2005.05.007. PMID 15935566. 
  4. Macvanin M, Johanson U, Ehrenberg M, Hughes D. Fusidic acid-resistant EF-G perturbs the accumulation of ppGpp. Molecular microbiology. July 2000, 37 (1): 98–107. doi:10.1046/j.1365-2958.2000.01967.x. PMID 10931308. 

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