Bacterial 50S ribosomal subunit peptidyl transferase center (PTC) (PTC)

The bacterial 50S ribosomal subunit peptidyl transferase center (PTC) is the catalytic core of the ribosome, primarily composed of highly conserved segments of the 23S ribosomal RNA (rRNA) (Polikanov et al., 2014). Its fundamental biological role is to catalyze peptide bond formation by orienting the aminoacyl-tRNA and peptidyl-tRNA substrates for a nucleophilic attack, effectively acting as a ribozyme (Wilson, 2014). In the context of infectious diseases, the PTC is a critical therapeutic target for numerous antibiotic classes, including oxazolidinones, macrolides, and lincosamides, which disrupt bacterial protein synthesis (Dunkle et al., 2010). These drugs bind within the PTC pocket to physically block the progression of the nascent peptide chain or prevent substrate binding. While highly effective against a broad spectrum of pathogens, drugs targeting the PTC can exhibit toxicity due to structural similarities between bacterial ribosomes and human mitochondrial ribosomes (Böttger et al., 2001). Resistance is a significant clinical challenge, often mediated by mutations in the 23S rRNA or the action of methyltransferases like Cfr (Long et al., 2006). Understanding the structural nuances of the PTC is essential for the development of next-generation antibiotics that can overcome existing resistance mechanisms.

Other names

Peptidyl transferase centerPTC23S rRNA peptidyl transferase centerRibosomal catalytic center

Antibiotics targeting the PTC inhibit bacterial protein synthesis by binding to the 23S rRNA, which either sterically hinders the binding of aminoacyl-tRNA to the A-site, prevents the formation of the peptide bond, or obstructs the exit tunnel for the nascent polypeptide chain (Wilson, 2014; Dunkle et al., 2010).