What are the roles of antibiotics and toxins in translation (protein synthesis)?

Roles of antibiotics  and toxins-

1.Streptomycin- A basic antibiotic  binds with 30s subunit of the bacterial ribosome change the structure and causes misreading of m-RNA .

2.Tetracyclines-  It  binds with 30S ribosomal subunit and interferes in attachment of t-RNA to m-RNA  ribosome complex.(aminoacyl t-RNA binding)

3.Erythromycin-  Binds to 50S subunit and prevents peptide chain elongation.

4.Chloramphenicol-  It binds to 50S portion of ribosome and inhibits peptide bond formation through inhibition of peptidyl transferase .

Image source-http://chemistry.elmhurst.edu/vchembook/654antibiotic.htm

5.Cycloheximide- Blocks the peptidyl transferase of 80S ribosome .

6.Fusidic acid - It binds to EF-G and blocks translocation (A site and P site translocate to P site and E site respectively).

7.Puromycin-  It  is an antibiotic which enters the A site and transfers to the growing chain, causing the formation of a puromycylated nascent chain and premature chain release.

8.Diptheria toxin - It is an exotoxin of Corynebacterium diphtheriae stops the protein synthesis in eukaryotes by inactivating the elongation factor eEF2.

9.Ricin - A toxic protein of castor bean (Richinus communis) that inactivates the 60S subunit of eukaryotic ribosome by depurinating a specific adenosine in 28S rRNA.

MCQ
1. Which antibiotic is responsible for premature termination of trnslation in bacteria?
a.Tetracycline  b.penicillin c. puromycin d. ricin
Ans. Puromycin

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