70S ribosome inter-subunit bridge B5 (Bridge B5) (Bridge B5)

The 70S ribosome inter-subunit bridge B5 is a fundamental structural element in the bacterial ribosome that facilitates communication and stability between the small (30S) and large (50S) subunits (Yusupov et al., 2001, Science). It is primarily an RNA-RNA contact formed between helix 44 (h44) of the 16S ribosomal RNA and helix 67 (H67) of the 23S ribosomal RNA (Dunkle et al., 2011, Science). This bridge is situated near the decoding center and is crucial for the dynamic movements of the ribosome during the elongation cycle, particularly the ratcheting motion and translocation of tRNAs (Liu & Agrawal, 2010, PNAS). Due to its essential role in protein synthesis, bridge B5 is a significant site for antibiotic action. Drugs such as aminoglycosides (e.g., gentamicin and paromomycin) bind to the h44 component of the bridge, interfering with the accuracy of decoding and the movement of the mRNA-tRNA complex (Carter et al., 2000, Nature). Targeting this bridge is a proven strategy for treating bacterial infections, though challenges remain regarding drug toxicity and the emergence of resistant bacterial strains (Wilson, 2014, Nature Reviews Microbiology).

Other names

B5 bridgeIntersubunit bridge B5h44-H67 bridge

Aminoglycosides bind to the helix 44 (h44) component of bridge B5, inducing a conformational change in adenine residues (A1492 and A1493) that mimics the state of correct codon-anticodon pairing, leading to translational misreading and the inhibition of ribosomal translocation (PubMed: 10952302, 11136714).