Valle Mikel, Sengupta Jayati, Swami Neil K, Grassucci Robert A, Burkhardt Nils, Nierhaus Knud H, Agrawal Rajendra K, Frank Joachim
Howard Hughes Medical Institute, Health Research, Inc., Empire State Plaza, Albany, NY 12201-0509, USA.
EMBO J. 2002 Jul 1;21(13):3557-67. doi: 10.1093/emboj/cdf326.
During the elongation cycle of protein biosynthesis, the specific amino acid coded for by the mRNA is delivered by a complex that is comprised of the cognate aminoacyl-tRNA, elongation factor Tu and GTP. As this ternary complex binds to the ribosome, the anticodon end of the tRNA reaches the decoding center in the 30S subunit. Here we present the cryo- electron microscopy (EM) study of an Escherichia coli 70S ribosome-bound ternary complex stalled with an antibiotic, kirromycin. In the cryo-EM map the anticodon arm of the tRNA presents a new conformation that appears to facilitate the initial codon-anticodon interaction. Furthermore, the elbow region of the tRNA is seen to contact the GTPase-associated center on the 50S subunit of the ribosome, suggesting an active role of the tRNA in the transmission of the signal prompting the GTP hydrolysis upon codon recognition.
在蛋白质生物合成的延伸循环中，由mRNA编码的特定氨基酸由一种复合物传递，该复合物由同源氨酰tRNA、延伸因子Tu和GTP组成。当这种三元复合物与核糖体结合时，tRNA的反密码子末端到达30S亚基的解码中心。在此，我们展示了对与抗生素奇霉素结合的大肠杆菌70S核糖体三元复合物的冷冻电镜（EM）研究。在冷冻电镜图谱中，tRNA的反密码子臂呈现出一种新的构象，似乎有助于初始密码子-反密码子相互作用。此外，还观察到tRNA的肘部区域与核糖体50S亚基上的GTP酶相关中心接触，这表明tRNA在密码子识别时促使GTP水解的信号传递中发挥了积极作用。
