MEDizzy - A 27-year-old man is seen by his physician for a week-long

Feed Library Learning Discuss Leaderboard Journal

NUCLEIC ACID

A 27-year-old man is seen by his physician for a week-long cough, sore throat, and difficulty swallowing. He is diagnosed with diphtheria, which has been reactivated because of waning immunity. One way in which diphtheria toxin leads to cell death is through the inhibition of eEF-2. Which statement best explains the function of eEF-2?

ExplanationEukaryotic elongation factor 2 (eEF-2) is required for eukaryotic translation in that it facilitates the translocation of peptidyl-tRNA along the mRNA. The elongation reaction requires GTP hydrolysis. The corresponding elongation factor in bacteria is EF-G. Diphtheria toxin ADP-ribosylates eEF-2, leading to its inactivation. Initiation of eukaryotic protein synthesis requires several initiation factors, designated eIF-1, eIF-2, etc. Peptidyl transferase is an rRNA (within the large ribosomal subunit) involved in the formation of the peptide bond between the amino acid groups within the A and P sites of the ribosome. This activity is not affected by the toxin. Chloramphenicol inhibits prokaryotic peptidyl transferase. Prokaryotes are not affected by diphtheria toxin because they do not contain eEF-2.