16S ribosomal RNA (16S rRNA)

The 16S ribosomal RNA (16S rRNA) is the essential ribonucleic acid component of the bacterial 30S ribosomal subunit, acting as both a structural scaffold and a functional catalyst during protein synthesis. It is responsible for the critical process of decoding, where it ensures the correct pairing of mRNA codons with tRNA anticodons at the aminoacyl (A) site, and it also plays a key role in the initiation of translation by binding to the Shine-Dalgarno sequence of mRNA. Due to significant structural differences between bacterial 16S rRNA and eukaryotic 18S rRNA, it serves as a highly selective target for numerous antibiotic classes. Aminoglycosides, such as gentamicin and amikacin, bind to the decoding center of the 16S rRNA, inducing conformational changes that cause the ribosome to misread the genetic code, leading to the synthesis of aberrant proteins. Tetracyclines and glycylcyclines bind to a distinct site on the 30S subunit, sterically preventing the attachment of aminoacyl-tRNAs and thereby halting the elongation of the polypeptide chain. Resistance to these drugs is a major clinical concern and typically involves mutations in the 16S rRNA gene, enzymatic modification of the antibiotics, or the acquisition of methyltransferases that chemically alter the rRNA to block drug binding.

Other names

30S ribosomal RNABacterial 30S ribosomal rRNArrsSmall subunit ribosomal RNASSU rRNA

Antibiotics targeting the 16S rRNA primarily inhibit protein synthesis through several mechanisms: aminoglycosides bind to the A-site decoding center to induce mRNA misreading and inhibit translocation; tetracyclines and glycylcyclines sterically block the binding of aminoacyl-tRNA to the A-site; and aminocyclitols like spectinomycin inhibit the translocation of the peptidyl-tRNA from the A-site to the P-site.