Ribosomes cannot interact simultaneously with elongation factors EF Tu and EF G

Area of Science:

• Molecular Biology
• Protein Synthesis
• Bacterial Ribosomes

Background:

• Elongation factors EF G and EF Tu play crucial roles in bacterial protein synthesis.
• EF G mediates translocation, while EF Tu facilitates aminoacyl-tRNA binding.

Purpose of the Study:

• To investigate the potential for simultaneous binding of EF G and EF Tu to the 70S ribosome.
• To elucidate the interaction dynamics between these elongation factors and the ribosome during protein synthesis.

Main Methods:

• Studied the binding of EF G and GDP to Escherichia coli 70S ribosomes.
• Assessed the effect of EF G, GDP, and fusidic acid on EF Tu.GTP.aminoacyl-tRNA interaction with the 30S ribosomal subunit.

Main Results:

• Prior binding of EF G and GDP inhibits subsequent aminoacyl-tRNA binding mediated by EF Tu.
• EF Tu.GTP.aminoacyl-tRNA interaction with the 30S subunit is unaffected by EF G, GDP, and fusidic acid under specific conditions.
• Evidence suggests EF G and EF Tu cannot bind to the ribosome at the same time.

Conclusions:

• EF G and EF Tu compete for the same or overlapping ribosomal binding sites.
• These elongation factors must alternate their binding to the ribosome during each elongation cycle for efficient protein synthesis.