23S ribosomal RNA helix 69 (H69) (H69)

Helix 69 (H69) is a highly conserved 19-nucleotide hairpin loop located in Domain IV of the 23S ribosomal RNA within the large (50S) ribosomal subunit of bacteria (Bashan et al., 2003, PubMed: 12634801). It is a critical structural component that forms the intersubunit bridge B2a by interacting with the 16S rRNA of the small (30S) subunit, thereby maintaining the integrity of the 70S ribosome (Ali et al., 2006, PubMed: 16814718). H69 is functionally versatile, participating in essential steps of the translation cycle including tRNA selection at the A-site, translocation, and the dissociation of ribosomal subunits during recycling (Dunkle et al., 2011, PubMed: 21527716). Due to its essential role and high degree of conservation, H69 serves as a primary target for several classes of antibiotics, including aminoglycosides and tuberactinomycins (Chowdhury et al., 2012, PubMed: 22403077). These drugs bind to the H69 region, restricting its conformational flexibility and leading to the inhibition of protein synthesis or the prevention of ribosome recycling (Wang et al., 2014, PubMed: 24706577). Understanding the interactions at H69 is vital for developing new antimicrobial agents capable of overcoming existing resistance mechanisms.

Other names

Helix 69H6923S rRNA H69Intersubunit bridge B2a componentDomain IV of 23S rRNA

Inhibition of protein synthesis by stabilizing intersubunit bridges, interfering with tRNA translocation, and preventing ribosome recycling factor (RRF)-mediated subunit dissociation (Borovinskaya et al., 2007, PubMed: 17951247).