Mechanism of Action of Oxazolidinones

Oxazolidinone antibiotics (such as eperezolid, linezolid, posizolid, radezolid, torezolid etc.) have been known to contain the oxzolidinone ring in them structurally and hence their name. They are potent antibiotics which are saved as drugs of last resort against gram-positive bacteria. They are not to be used against bacteria which are sensitive to narrow spectrum antibiotics and penicillins and cephalosporins. Mechanistically oxazolidinone antibiotics show their action by inhibiting protein biosynthesis in the bacteria, which in turn causes cell death.

Mechanism of Action of Oxazolidinone Antibiotics

Oxazolidinone antibiotics act by inhibiting protein biosynthesis in the bacterial cell. They do this by binding to the 50S ribosomal subunit and prevent the formation of the initiation complex itself which is the first step in protein biosynthesis. During the formation of the initiation complex, the 50S ribosomal unit tries to combine along with the 30S ribosomal subunit which has along with it the f-met tRNA. However, due to the presence of the oxazolidinones, this formation of the initiation complex is blocked and thus protein biosynthesis comes to a complete stand still. This results in lack of protein expression by the bacterial cell leading to cell death.

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The above animations has been supplied by Dr. Gary E. Kaiser from the Community College of Baltimore County– and it illustrates the mechanism of action of tetracyclines. The transcript of the animation is as follows:

” The oxazolidinones bind to the 50S ribosomal subunit and interfere with formation of the complex that associates the mRNA, the fmet-tRNA, and the 50S ribosomal subunit. ”

References

  1. Colca JR, McDonald WG, Waldon DJ, et al. Cross-linking in the living cell locates the site of action of oxazolidinone antibiotics. Journal of Biological Chemistry 278 (24), 2003, 21972–21979.
  2. DL Shinabarger, KR Marotti, RW Murray, AH Lin, EP Melchior, SM Swaney, DS Dunyak, WF Demyan, JM Buysse. Mechanism of action of oxazolidinones: effects of linezolid and eperezolid on translation reactions. Antimicrob. Agents Chemother., Oct 1997, 2132-2136, Vol 41, No. 10

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