4. Protein Synthesis 3 | Summary and Q&A

TL;DR

EF-Tu is a crucial protein in the ribosome that delivers aminoacyl tRNAs to the A-site for peptide bond formation. Conformational changes and codon-anticodon recognition play key roles in this process.

Key Insights

• 🥦 EF-Tu is the most abundant protein in E. coli, controlling the delivery of aminoacyl tRNAs to the ribosome.
• 💱 Conformational changes in the decoding center of the ribosome stabilize codon-anticodon interactions, accelerating GTP hydrolysis by EF-Tu.
• 👻 The GTPase center of EF-Tu undergoes conformational changes, allowing for GTP hydrolysis and subsequent accommodation of the aminoacyl tRNA in the A-site.
• ❓ Near-cognate tRNAs are quickly rejected by the ribosome, preventing incorrect amino acid incorporation.

Transcript

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Questions & Answers

Q: What is the role of EF-Tu in translation?

EF-Tu delivers aminoacyl tRNAs to the ribosome's A-site during the elongation phase of translation.

Q: How does EF-Tu bind to the ribosome?

Initial binding between EF-Tu and the ribosome occurs independently of mRNA, facilitated by ribosomal proteins L7 and L12.

Q: What happens during codon recognition?

Codon recognition involves the sampling of codon-anticodon pairs in the A-site. If a cognate anticodon is present, conformational changes in EF-Tu activate the GTPase center.

Q: What is the consequence of delivering a near-cognate tRNA to the ribosome?

If a near-cognate tRNA is delivered, the ternary complex rapidly dissociates from the ribosome, preventing peptide bond formation.

Summary & Key Takeaways

• EF-Tu is responsible for delivering aminoacyl tRNAs to the ribosome's A-site during translation.

• Initial binding of the ternary complex (EF-Tu-GTP-aminoacyl tRNA) to the ribosome occurs independently of mRNA.

• Codon recognition in the A-site leads to conformational changes in EF-Tu, activating the GTPase center, which stimulates GTP hydrolysis.

• The correct aminoacyl tRNA is fully accommodated in the A-site, allowing for peptide bond formation.

• If a near-cognate tRNA is delivered to the A-site, the ternary complex rapidly dissociates from the ribosome.