16S ribosomal RNA aminoacyl-tRNA site (16S rRNA A-site) (16S rRNA A-site)

The 16S ribosomal RNA (rRNA) A-site is a critical functional region within the 30S subunit of the bacterial ribosome, responsible for the decoding of genetic information during protein synthesis [1, 8]. It serves as the binding site for aminoacyl-tRNA molecules, where the fidelity of translation is ensured through precise codon-anticodon recognition [10, 15]. This site is the primary target for several classes of potent antibiotics, most notably aminoglycosides and tetracyclines [7, 17]. Aminoglycosides bind to the A-site and induce a conformational change that causes the ribosome to misread mRNA, leading to the production of erroneous, toxic proteins and eventual bacterial cell death [1, 20]. Tetracyclines, on the other hand, physically block the entry of tRNAs into the A-site, thereby halting protein elongation [15, 17]. Resistance to drugs targeting this site often arises through enzymatic modification of the antibiotics or post-transcriptional methylation of the 16S rRNA by methyltransferases, which prevents drug binding [4, 6].

Other names

Decoding site30S A-site16S rRNA decoding regionAminoacyl-tRNA binding site

Aminoglycosides bind to the A-site of the 16S rRNA, inducing a conformational change in residues A1492 and A1493 that mimics cognate tRNA binding, leading to mRNA misreading and inhibition of translocation [1, 3, 20]. Tetracyclines bind to the 30S subunit and sterically block the binding of aminoacyl-tRNA to the A-site [7, 17].