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(zhuǎn)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(huán)因子一起以GTP依賴方式促進(jìn)核糖體再循環(huán)[1]。
進(jìn)化
EF-G有一個(gè)復(fù)雜的進(jìn)化史，現(xiàn)代細(xì)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(jìn)化過程中發(fā)生了亞功能化[2]。
臨床意義
EF-G可被夫西地酸抑制，但有細(xì)菌也出現(xiàn)了耐藥性[3][4]。
參考文獻(xiàn)
- ↑ 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.
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