Bacterial 16S ribosomal RNA A-site (16S rRNA A-site) (16S rRNA A-site)

The Bacterial 16S ribosomal RNA A-site is a highly conserved region within the 30S ribosomal subunit that serves as the primary decoding center during protein translation (Vicens & Westhof, 2001, Chem & Bio). Its fundamental role is to ensure the accuracy of the genetic code by facilitating the selection of the correct aminoacyl-tRNA based on the mRNA codon (PubMed, PMC351914). This site is the principal pharmacological target for aminoglycoside antibiotics, which bind to the internal loop of the A-site and stabilize a 'flipped-out' conformation of adenine residues A1492 and A1493 (StatPearls, 2023). This structural alteration reduces the energy barrier for non-cognate tRNA binding, causing the ribosome to misread mRNA and produce aberrant proteins that disrupt bacterial cell membrane integrity (NIH, NBK541077). While highly effective against Gram-negative and some Gram-positive bacteria, drugs targeting this site can cause toxicity in humans due to structural similarities between the bacterial A-site and the human mitochondrial 12S rRNA A-site (PubMed, 12596201). Therapeutic challenges include the emergence of resistance mediated by 16S rRNA methyltransferases, which chemically modify the A-site to prevent drug binding (PubMed, 17307716).

Other names

Decoding regionA-site16S rRNA decoding centerAminoacyl-tRNA binding site30S A-site

Aminoglycosides bind to the 16S rRNA A-site, inducing a conformational change in residues A1492 and A1493 that mimics correct codon-anticodon pairing, leading to mistranslation and protein synthesis inhibition (StatPearls, 2023; Vicens & Westhof, 2001).