Bacterial 30S ribosomal subunit 16S rRNA helix 44 decoding A-site (16S rRNA A-site) (16S rRNA A-site)

The Bacterial 30S ribosomal subunit 16S rRNA helix 44 decoding A-site is a highly conserved region of the bacterial ribosome essential for the accuracy of protein synthesis (PubMed: 11441179). Located within the 16S rRNA, this site functions as the decoding center where the ribosome discriminates between correct (cognate) and incorrect (non-cognate) tRNA molecules based on the mRNA codon. During the decoding process, two specific adenine residues, A1492 and A1493, undergo a conformational shift to stabilize the codon-anticodon interaction. This site is the primary pharmacological target for aminoglycoside antibiotics, which bind to the A-site and lock these adenine residues in an active conformation regardless of the tRNA match (PubMed: 11557144). This interaction results in significant mistranslation of proteins and the disruption of bacterial cell membrane integrity, ultimately leading to bacterial cell death (StatPearls: Aminoglycosides).

Other names

16S ribosomal RNA decoding centerHelix 44 A-siteh44 decoding site30S A-siteAminoglycoside binding site

Aminoglycosides bind to the internal loop of helix 44 in the 16S rRNA, inducing a conformational change in residues A1492 and A1493 (PubMed: 11441179). This change mimics the state induced by correct codon-anticodon pairing, leading to the incorporation of incorrect amino acids (mistranslation) and the inhibition of ribosomal translocation (PubMed: 11557144).