Bacterial 50S ribosomal subunit 23S rRNA peptide exit tunnel (NPET) (NPET)

The bacterial 50S ribosomal subunit 23S rRNA peptide exit tunnel (NPET) is a structural conduit within the large ribosomal subunit through which the nascent polypeptide chain travels as it is synthesized at the peptidyl transferase center. This tunnel is approximately 80-100 Å long and is primarily lined by 23S ribosomal RNA, with structural contributions from ribosomal proteins L4 and L22. It serves as a critical site for antibiotic action; several classes of clinically important antibiotics, most notably macrolides, bind within the tunnel to physically obstruct the elongation of the protein chain. This blockage leads to the premature release of peptidyl-tRNA and the cessation of bacterial protein synthesis. Resistance to these drugs often arises through modifications of the tunnel's lining, such as methylation of the 23S rRNA at position A2058, which prevents drug binding. Understanding the NPET is essential for developing new antimicrobial agents that can overcome existing resistance mechanisms.

Other names

Nascent peptide exit tunnelRibosomal exit tunnel50S exit tunnelNPET

Inhibition of bacterial protein synthesis by binding to the 23S rRNA within the 50S ribosomal subunit and physically blocking the nascent peptide exit tunnel, which leads to premature dissociation of peptidyl-tRNA and cessation of translation elongation.