Chemical inhibitors of Small ribosomal subunit protein bS21m (MRP-S21) function through various mechanisms to disrupt the protein's involvement in mitochondrial protein synthesis. Chloramphenicol, Tetracycline, Erythromycin, Azithromycin, Linezolid, and Clindamycin inhibit MRP-S21 by directly interacting with the mitochondrial ribosome. Chloramphenicol achieves this inhibition by hindering peptide bond formation within the mitochondrial ribosome, a critical process in which MRP-S21 plays a role. Tetracycline and Erythromycin inhibit MRP-S21 by binding to the mitochondrial ribosome, thereby disrupting aminoacyl-tRNA's access to the ribosomal site, a vital step in protein synthesis. In a similar manner, Azithromycin and Linezolid obstruct MRP-S21's function by hindering the peptidyl transferase activity of the mitochondrial ribosome. Clindamycin targets MRP-S21 by affecting peptide bond formation, consequently disrupting the process of protein synthesis.
Other selected inhibitors, such as Doxycycline, Minocycline, Puromycin, Daptomycin, Fusidic Acid, and Rifampicin, utilize different mechanisms to inhibit MRP-S21. Doxycycline and Minocycline achieve inhibition by binding to the mitochondrial ribosome, preventing the incorporation of amino acids into growing peptide chains, thereby impacting MRP-S21's synthesis function. Puromycin disrupts the peptide elongation process, a key phase in protein synthesis involving MRP-S21. Daptomycin's mode of inhibition involves disrupting the mitochondrial membrane potential, essential for the protein synthesis process involving MRP-S21. Fusidic Acid targets the elongation factor G (EF-G) in the mitochondrial ribosome, affecting the translocation step in protein synthesis. Rifampicin inhibits MRP-S21 indirectly by binding to mitochondrial RNA polymerase, thus influencing the overall process of protein synthesis in which MRP-S21 is integral. Each of these chemicals, through their specific actions, contributes to the inhibition of MRP-S21, thereby impacting its role in mitochondrial protein synthesis.