Bacterial 50S ribosomal subunit helix 69 (H69) (H69)

Helix 69 (H69) is a highly conserved 19-nucleotide hairpin loop located within Domain IV of the 23S ribosomal RNA of the bacterial 50S subunit (Bashan et al., 2003, Molecular Cell). It forms the central intersubunit bridge B2a, which is essential for the association of the 30S and 50S subunits to form the functional 70S ribosome (Ali et al., 2006, Molecular Cell). H69 is dynamic and undergoes conformational changes during the translation cycle, facilitating tRNA selection and translocation (Dunkle et al., 2014, PNAS). Because of its critical role in protein synthesis and its high degree of conservation across bacterial species, it serves as a potent target for several classes of antibiotics, including tuberactinomycins like viomycin and certain aminoglycosides (Stanley et al., 2010, Nature Structural & Molecular Biology). Drugs targeting this region typically inhibit translocation or ribosome recycling, leading to bacterial cell death (Akbergenov et al., 2011, Antimicrobial Agents and Chemotherapy). Resistance often arises through methylation of specific residues within H69 or mutations in the rRNA sequence (Noller, 2005, Science).

Other names

Helix 69 of 23S rRNAH69 bridgeIntersubunit bridge B2a23S ribosomal RNA helix 69Bacterial 50S ribosomal subunit near the H69 bridge

Inhibition of translocation and ribosome recycling by stabilizing the intersubunit bridge B2a and interfering with tRNA movement (Stanley et al., 2010, Nature Structural & Molecular Biology; Akbergenov et al., 2011, Antimicrobial Agents and Chemotherapy).