Elongation Process and its Related Factors of Protein Synthesis

During translation, molecules known as transfer RNAs, or tRNAs, read the codons of an mRNA in order (from the 5′ end to the 3′ end).

Each tRNA molecule has an anticodon, which is a sequence of three nucleotides that base pairs with an mRNA codon. The codon-defined amino acid is carried on the other end of the tRNA. tRNAs form bonds with mRNAs inside the ribosome, a protein-and-RNA complex. The amino acids of tRNAs are chemically joined to the developing polypeptide chain as they enter slots in the ribosome and bind to codons. The end result is a polypeptide with an amino acid sequence that corresponds to the mRNA codon sequence.

Stages of Translation

The three stages of translation are identical, but they are referred to as initiation, elongation, and termination.

Initiation (“beginning”): The ribosome joins the mRNA and the first tRNA to begin translation.

Elongation (“middle”) occurs when tRNAs transport amino acids to the ribosome and connect them to form a chain.

Termination (“end”): the completed polypeptide is released to perform its function within the cell in the final stage.

Like initiation, elongation requires the use of elongation factors, which are non-ribosomal proteins. Eukaryotic EF1A (eEF1A) forms ternary complexes with aminoacyl-tRNAs and GTP. These ternary complexes enter the ribosome’s empty A site, where GTP is hydrolyzed and eEF1A is released if an appropriate codon-anticodon interaction develops between the aminoacyl-tRNA entering the A site and the codon in the A site. The peptidyl-transferase site of the ribosome catalyses peptide bond synthesis as the free amino group of the incoming aminoacyl-tRNA attacks the ester bond attaching the developing polypeptide to the tRNA in the ribosomal P site. As a result, the uncharged tRNA in the P site transfers to the E (exit) site and exits the ribosome. The expanding polypeptide chain in the P site is now one amino acid longer as it transfers to the aminoacyl-tRNA in the A site. The peptidyl-tRNA in the A site is then translocated back to the P site with the help of eEF2 and GTP. The A site becomes empty as the ribosome moves down the mRNA, and the process is repeated.

Translation elongation factors are the workhorses of protein synthesis on the ribosome. They aid in the extension of the polypeptide chain by one amino acid at a time. The general biochemical outline of the translation elongation cycle has been preserved in all biological kingdoms. Antibiotic effects on elongation have recently gained structural insight. These structures serve as a scaffold for understanding elongation factors’ biological activity until high-resolution structures of elongation factors in association with ribosomes are obtained. The structure of the yeast translocation factor and its interaction with the antifungal medication sordarin was recently revealed, revealing unexpected structural flexibility that may be critical to the translocation mechanism.

Elongation factors are a class of proteins that aid in the translational elongation of a developing polypeptide from the first to the last peptide bond at the ribosome during protein synthesis. The most common elongation factors in prokaryotes are EF-Tu, EF-Ts, and EF-G.

Bacteria and eukaryotes both use elongation factors, which are mostly similar but have different structures and scientific names.

Elongation is the most rapid step in translation.

In bacteria, it occurs at a rate of 15 to 20 amino acids per second (about 45-60 nucleotides per second). [requires citation] In eukaryotes, the rate is approximately two amino acids per second (about 6 nucleotides read per second). [requires citation] Elongation variables are important in organising this process’s events and ensuring good translation accuracy at these rates.

Elongation factor 4 (EF4) is a highly conserved protein found in bacteria, as well as mitochondria and chloroplasts in eukaryotes. Despite its unusual ability to catalyse the back-translocation reaction on post-translocation state ribosomes, the physiological significance of EF4 is unknown.

On ribosomes, two universal elongation factors (EF) drive the extension of a nascent polypeptide chain: EF-Tu (EF1A in Archaea and Eukarya) transports aminoacyl-tRNAs to the ribosomal A site, and EF-G (EF2) translocates the ribosomal tRNA2•mRNA complex by one codon length, allowing peptidyl-tRNA to move.

Conclusion

In living cells, therefore G protein elongation factor thermo unstable Tu (EF-Tu) catalyses the binding of aminoacyl-tRNA to the A-site of the ribosome. In structural and biochemical studies, the intricate interconnections required for canonical function have been described. EF-Tu, on the other hand, has evolved the ability to function on the extracellular surface of both eukaryotes and prokaryotes. EF-Tu can enter and remain on cell surfaces, where it interacts with membrane receptors and the extracellular matrix of plant and animal cells.