BIOCHEM FINAL - elongation & termination

EF-Tu is an elognation factor (GTPase) that delivers aminoacyl-tRNA to the ribosome A-site, checks codon-anticodon pairing, and realeases tRNA after GTP hyrolysis

What is EF-Tu and what does it do?

EF-Ts exchanges GDP for GTP on EF-Tu, allowing it to bind another aminoacyl-tRNA

How is EF-Tu recharged?

catalyzed by 23S rRNA in the 50S subunit; amino group A-site amino acid attacks carbonyl of P-site polypeptide. polypeptide transferred to A-site tRNA

How is the peptide bond formed in bacterial translation?

EF-G is a GTPase that mimics tRNA and drives ribosome translocation along mRNA after peptide bond formation

What is EF-G and what is its function?

GTP hydrolysis provides energy to move the ribosome 3 nucleotides forward, shifting tRNAs from A to P and P to E sites

How does EF-G use GTP?

Bind the A-site at a stop codon, hydrolyze the polypeptide from P-site tRNA, and together with EF-G/RRF, dissociate tRNAs, mRNA, and split the ribosome

What do release factors do in termination?

In bacteria, ribosomes can bind a new Shine-Dalgarno sequence on mRNA before transcription is finished by preceding ribosomes

What is co-transcriptional translation?

N-terminal signal peptide recognized by SRP - translation pauses - ribosome moves to translocation complex, protein exported, signal cleaved

How secreted proteins handled in bacteria?

4 high-energy bonds

• 2ATP to charge tRNA

• 1 GTP for EF-Tu codon-anticodon checking

• 1GTP for EF-G translocation

How much energy is required per amino acid during elongation