Bacterial ribosomal 50S subunit (23S ribosomal RNA)

The **bacterial ribosomal 50S subunit** (specifically the 23S rRNA) is the molecular target of clarithromycin, a macrolide antibiotic. Clarithromycin binds reversibly to domain V of the 23S rRNA within the 50S ribosomal subunit, blocking peptide exit and interfering with translocation during protein synthesis. This results in inhibition of bacterial growth (bacteriostatic effect), though at higher concentrations or against specific organisms it may achieve bactericidal activity[1][2][4][5][6]. Resistance can develop through mutation or methylation of the rRNA binding site, which alters drug affinity and undermines efficacy[2][3]. Clarithromycin and other macrolides are thus considered to target the ribosomal machinery of bacteria directly, perturbing translation as their primary mechanism of action. The 50S ribosomal subunit is not a protein or \"receptor\" in the classical sense, but a ribonucleoprotein complex serving as the platform for peptide synthesis and translation regulation.

Other names

50S ribosomal subunit50S ribosome23S ribosomal RNAbacterial ribosome large subunit

Inhibition of bacterial protein synthesis by binding to 23S rRNA of the 50S subunit, blocking translocation and polypeptide chain elongation[1][2][4][5][6] - Context-specific translation arrest modulating expression of some bacterial genes, including resistance genes[2]