Pseudomonas aeruginosa exotoxin A inactivates elongation factor 2. This contributes to pathogenicity by inhibiting which cellular process?

• A. DNA replication
• B. Protein synthesis in host cells
• C. RNA transcription
• D. Lipids synthesis

Answer: (B)

The key idea is that Pseudomonas exotoxin A halts host protein production by disabling elongation during translation. It does this by ADP-ribosylating elongation factor 2, which is essential for the translocation step that moves the growing peptide from the A site to the P site on the ribosome. Without EF-2 function, peptide chain elongation stops, so protein synthesis in the affected host cells ceases. This loss of protein production leads to cell injury and death, contributing to tissue damage during infection. DNA replication would not be directly affected, transcription remains ongoing with RNA polymerase, and lipid synthesis isn’t targeted by EF-2’s role, so those processes aren’t the primary impact of this toxin.