23S ribosomal RNA


The 23S rRNA is a 2904 nt long component of the large subunit of the bacterial/archean ribosome. The ribosomal peptidyl transferase activity resides in domain V of this rRNA, and this domain is the most common binding site for antibiotics that inhibit translation. A well-known member of this antibiotic class, chloramphenicol, acts by inhibiting peptide bond formation, with recent 3D-structural studies showing two different binding sites depending on the species of ribosome. Linezolid and quinupristin-dalfopristin also bind to the 23S rRNA, and cross-resistance has been demonstrated between these antibiotics. Compared to 16S rRNA genes, 23S rRNA genes typically have higher sequence variations including insertions and/or deletions.
The eukaryotic homolog of the 23S rRNA is the 28S ribosomal RNA, with a region filled by the 5.8S ribosomal RNA.

23S rRNA Functions

In general, rRNA has an essential function of peptidyl transferase, the stimulating core of the ribosome plays role in the peptide bond configuration. Both peptidyl-tRNA and aminoacyl-tRNA are important for synthesizing protein and transpeptidation response. However, 23S rRNA positions which are G2252, A2451, U2506, and U2585 have a significant function for tRNA binding in P site of the large ribosomal subunit. These modification nucleotides in site P can inhibit peptidyl-tRNA from binding and also remains U2555 modification intervene with transferring peptidyl-tRNA to puromycin. Furthermore, the chemical modification of half of these positions G2251, G2253, A2439, and U2584 can not prevent the tRNA binding. Peptidyl-tRNA of 50s subunits which binds to the P site preserve eight positions of 23S rRNA from chemical modification. On the other hand, 23S rRNA impacts on mutation for cell growth. Mutations A1912G, A1919G and Ψ1917C have a powerful growth phenotypes and they prevent translation while mutation A1916G has a simple growth phenotype and it leads to defect in the 50S subunits.