Cryo-EM reveals an active role for aminoacyl-tRNA in the accommodation process

• Published in: The EMBO journal Vol. 21; no. 13; pp. 3557 - 3567
• Main Authors: Valle, Mikel, Sengupta, Jayati, Swami, Neil K., Grassucci, Robert A., Burkhardt, Nils, Nierhaus, Knud H., Agrawal, Rajendra K., Frank, Joachim
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-07-2002; Blackwell Publishing Ltd; Oxford University Press
• Subjects: Amino acids; Anticodon - genetics; Biosynthesis; Codon - genetics; Cryoelectron Microscopy; decoding; E coli; electron microscopy; elongation factor Tu; Escherichia coli - chemistry; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - ultrastructure; Guanosine Diphosphate - chemistry; Guanosine Triphosphate - metabolism; Image Processing, Computer-Assisted; Macromolecular Substances; Models, Molecular; Nucleic Acid Conformation; Peptide Chain Elongation, Translational; Peptide Elongation Factor Tu - chemistry; Peptide Elongation Factor Tu - ultrastructure; Protein Conformation; Pyridones - pharmacology; ribosome; Ribosomes - chemistry; Ribosomes - drug effects; Ribosomes - ultrastructure; RNA, Transfer - chemistry; RNA, Transfer, Amino Acyl - chemistry; RNA, Transfer, Amino Acyl - metabolism; RNA, Transfer, Amino Acyl - physiology; RNA, Transfer, Amino Acyl - ultrastructure; RNA, Transfer, Phe - chemistry; RNA, Transfer, Phe - metabolism; Structure-Activity Relationship; tRNA
• ISSN: 0261-4189; 1460-2075; 1460-2075
• 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.