EF-G為延伸因子G（英語：elongation factor G）的縮寫，是原核延伸因子中的轉位酶。
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.
除了在翻譯中的作用外，EF-G還與核糖體再循環因子一起以GTP依賴方式促進核糖體再循環[1]。
進化
EF-G有一個複雜的進化史，現代細菌基因組中存在的大量該延伸因子的旁系同源基因暗示了不同的EF-G變體可能在進化過程中發生了亞功能化[2]。
臨床意義
EF-G可被夫西地酸抑制，但有細菌也出現了耐藥性[3][4]。
參考文獻
- ↑ 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.
- ↑ 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.
- ↑ 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.
- ↑ 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.
外部連結
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