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

The 16S ribosomal RNA (rRNA) decoding A-site is a highly conserved functional region within the 30S small ribosomal subunit of bacteria [1, 4]. Its primary biological role is to ensure the accuracy of protein synthesis by monitoring the base-pairing between the mRNA codon and the aminoacyl-tRNA anticodon [2, 9]. During translation, specific nucleotides (A1492 and A1493) flip out of the rRNA helix to stabilize the codon-anticodon interaction, a process essential for the selection of the correct tRNA [8, 9]. This site is the principal target for aminoglycoside antibiotics, which bind with high affinity to the internal loop of the A-site [1, 5]. By locking the decoding center in an "active" conformation regardless of the tRNA match, these drugs induce widespread mistranslation and inhibit translocation, leading to the production of toxic, misfolded proteins and bacterial cell death [3, 5]. Resistance to these drugs often arises through enzymatic modification of the rRNA by methyltransferases or through specific mutations that reduce drug binding affinity [1, 2].

Other names

16S rRNA decoding region30S A-siteAminoacyl-tRNA binding siteDecoding center16S rRNA aminoacyl-tRNA binding site

Aminoglycosides bind to the A-site of the 16S rRNA, inducing a conformational change in nucleotides A1492 and A1493. This change mimics the state of a correct codon-anticodon match, leading to the incorporation of incorrect amino acids (mistranslation) and the inhibition of ribosomal translocation, which ultimately results in bacterial cell death [1, 2, 5].