Mycobacterium tuberculosis 50S ribosomal subunit (Mtb 50S ribosome)

The Mycobacterium tuberculosis 50S ribosomal subunit is the larger component of the bacterial 70S ribosome, serving as the primary site for peptidyl transferase activity and the exit tunnel for nascent polypeptide chains (PubMed: 32814900). It is a complex ribonucleoprotein assembly composed of 23S ribosomal RNA (rRNA), 5S rRNA, and approximately 33 ribosomal proteins, providing a structural framework essential for bacterial protein synthesis. This subunit is a critical therapeutic target in the treatment of tuberculosis, particularly for multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains. Antibiotics such as oxazolidinones (e.g., linezolid) bind to the 50S subunit to inhibit the formation of the 70S initiation complex, thereby halting the production of essential bacterial proteins (StatPearls: NBK539793). However, the clinical utility of these drugs is often limited by the emergence of resistance through mutations in the 23S rRNA or ribosomal proteins, as well as potential host toxicities resulting from structural similarities between bacterial and human mitochondrial ribosomes (PubMed: 25135897, PubMed: 22247127).

Other names

Large ribosomal subunit50S subunitM. tuberculosis 50S ribosome23S rRNA-protein complex

Inhibition of the initiation of translation or peptidyl transferase activity by binding to the 50S ribosomal subunit, preventing the formation of the 70S initiation complex or blocking the elongation of the polypeptide chain.