Prokaryotic Ribozyme for Peptide Bond Formation: 23S rRNA Role

The ribozyme catalyzing peptide bond formation in prokaryotic protein synthesis is 23S rRNA within the 50S ribosomal subunit. This discovery revolutionized our view of ribosomes as RNA-based catalysts.​

Correct Answer

2. 23S rRNA performs peptidyl transferase activity in prokaryotes. It resides in the large 50S subunit’s peptidyl transferase center (PTC), accelerating peptide bonds between amino acids on tRNAs during translation elongation.

Option Breakdown

28S rRNA (Option 1)

28S rRNA is part of the eukaryotic 60S large ribosomal subunit. Prokaryotes lack 28S rRNA, using 23S instead, so it plays no role in bacterial protein synthesis.​

23S rRNA (Option 2)

In prokaryotic 70S ribosomes, 23S rRNA forms the PTC core. Its conserved structure positions A-site and P-site tRNAs for entropic catalysis, enabling rapid peptide bond formation without protein involvement.

16S rRNA (Option 3)

16S rRNA is in the prokaryotic 30S small subunit. It aids mRNA decoding and tRNA anticodon matching during initiation and elongation but does not catalyze peptide bonds.​

5.8S rRNA (Option 4)

5.8S rRNA occurs in eukaryotic 60S subunits, homologous to prokaryotic 23S rRNA’s domain but not involved in PTC catalysis. Prokaryotes do not have it.​