Skip to content
Login Register

#23S rRNA

2 public questions tagged with this topic.

Translation Basics

Large subunit rRNA catalyzing peptidyl transferase in prokaryotes is

Peptidyl transferase center that catalyzes peptide bond formation resides in large subunit rRNA, not proteins. In prokaryotes, domain V of 23S rRNA folds into catalytic crevice containing conserved A-loop and P-loop positioning CCA ends of A-site and P-site tRNAs for nucleophilic attack of alpha-amino on peptidyl ester. Crystallographic studies reveal no protein within 18 angstroms of active site. Mutation of key 23S adenines abolishes activity while protein removal retains catalysis. Equivalent in eukaryotes is 28S rRNA, confirming ribosome is ribozyme.

Ref: Watson Molecular Biology of the Gene, 7th ed., Chapter 15, 23S rRNA as peptidyl transferase ribozyme

View Details
Processing of rRNA and tRNA

Which rRNA is part of large subunit in prokaryotes?

The bacterial 70S ribosome consists of 30S small subunit and 50S large subunit. The large subunit comprises 23S rRNA of about 2900 nucleotides and 5S rRNA plus 33 ribosomal proteins. 23S rRNA dominates the particle, forming peptidyl transferase center in domain V, nascent peptide exit tunnel lining, and intersubunit bridges. 16S rRNA is confined to small subunit for decoding. Therefore, 23S marks the large subunit, whereas 16S marks small subunit. Eukaryotic counterpart is 28S rRNA in 60S, underscoring evolutionary conservation of large subunit catalytic RNA.

Ref: Watson Molecular Biology of the Gene, 7th ed., Chapter 15, Bacterial 50S subunit and 23S rRNA

View Details