Bacterial 70S ribosomal subunit (70S ribosome)

The bacterial 70S ribosomal subunit is a large ribonucleoprotein complex essential for protein synthesis in prokaryotes, composed of a small (30S) and a large (50S) subunit. The 30S subunit contains 16S rRNA and 21 proteins, while the 50S contains 23S and 5S rRNA and 34–36 proteins. The ribosome's main function is to catalyze mRNA-directed polymerization of amino acids into polypeptide chains, making it the central hub of translation and a critical target for many antibiotics. Numerous clinically important antibiotics act by binding to the 70S ribosome to inhibit various steps in translation, such as initiation, elongation, or termination. Targeting the bacterial ribosome allows selective inhibition of bacterial protein synthesis, but the high degree of rRNA and protein conservation across species requires careful drug design to maintain selectivity and prevent toxicity. Resistance frequently arises through mutation of ribosomal genes or acquisition of protective enzymes.

Other names

Prokaryotic ribosome70S ribosomeBacterial ribosome

Inhibition of peptide bond formation (50S subunit inhibitors such as macrolides, chloramphenicol); Inhibition of translation initiation or mRNA/tRNA translocation (30S subunit inhibitors such as aminoglycosides, kasugamycin, tetracyclines); Binding to ribosomal RNA or proteins, blocking functional sites or assembly