Process of bacterial protein synthesis and Drugs inhibiting it | Video

Check out the video about the process of bacterial protein synthesis and drugs inhibiting it.

Tetracyclines binds to a site on 30s ribosome which is complentary to the A site in 50s. This prevents the access of incoming tRNA to the A site of the mRNA-ribosome complex.

The primary site of action of all aminoglycoside is 30s ribosomal subunit. These drugs except streptomycin, also acts on 50s and 30s-50s interface. Binding of these drugs leads to misreading of the mRNA template thereby resulting in the abnormal initiation complexes and aberrant protein formation. These abnormal initiation complexes otherwise called as Streptomycin monosomes freezes the initiation. And these aberrant proteins gets inserted into the cell membrane, leading to altered permeability which further lead to progressive disruption of the cell envelope and other vital process.

Chloramphenicol bind to a site on the 50s ribosome namely the Peptidyl Transferase Centre or PTC. This prevents the transfer of amino acid on tRNA located on P site to tRNA on A site. In short, chloramphenicol inhibits PàA transfer.

Lincosamides namely Clindamycin binds to a site very adjacent to chloramphenicol and act in a similar way to chloramphenicol.

Macrolides and Ketolides binds to a site adjacent to chloramphenicol and Lincosamides on the 50s ribosome, but has a slightly different action. The binding site of macrolide is called as Nascent Peptide Exit Tunnel or NPET. After binding to this site, macrolides constrict the exit tunnel, thereby preventing the exit of the empty tRNA after the PàA transfer. Therefore the next step being the AàP transfer cannot take place. This causes the protein synthesis machinery to stop functioning further.

Oxazolidinones namely Linezolid binds to the 23s subunit of the 50s ribosomal P-site and prevents the formation of larger ribosomal-fMet-tRNA complex and thereby inhibiting the protein synthesis at the initiation step.


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impas Natesh Prabhu Administrator & Chief Editor | Clinical Pharmacologist | Diabetic-Sexual Medicine-Regenerative Therapy Consultant | President, Indian Medical Pharmacologists Association