Inhibition of peptide bond formation by pleuromutilins: the structure of the 50S ribosomal subunit from Deinococcus radiodurans in complex with tiamulin

• Published in: Molecular microbiology Vol. 54; no. 5; pp. 1287 - 1294
• Main Authors: Schlünzen, Frank, Pyetan, Erez, Fucini, Paola, Yonath, Ada, Harms, Jörg M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-12-2004; Blackwell Science
• Subjects: Bacteriology; Biological and medical sciences; Crystallography, X-Ray; Deinococcus - chemistry; Deinococcus - drug effects; Deinococcus radiodurans; Diterpenes - chemistry; Diterpenes - metabolism; Diterpenes - pharmacology; Fundamental and applied biological sciences. Psychology; Microbiology; Miscellaneous; Models, Molecular; Peptidyl Transferases - antagonists & inhibitors; Pleuromutilins; Polycyclic Compounds; Protein Conformation; Protein Synthesis Inhibitors - chemistry; Protein Synthesis Inhibitors - pharmacology; Ribosomes - chemistry; Ribosomes - metabolism; RNA, Ribosomal, 23S - chemistry; RNA, Ribosomal, 23S - metabolism; Tiamulin; Antifungal agent; Microbiology; Peptides; Bacteria; Micrococcales; Micrococcaceae; Deinococcus radiodurans; Subunit
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2004.04346.x

Summary
Tiamulin, a prominent member of the pleuromutilin class of antibiotics, is a potent inhibitor of protein synthesis in bacteria. Up to now the effect of pleuromutilins on the ribosome has not been determined on a molecular level. The 3.5 Å structure of the 50S ribosomal subunit from Deinococcus radiodurans in complex with tiamulin provides for the first time a detailed picture of its interactions with the 23S rRNA, thus explaining the molecular mechanism of the antimicrobial activity of the pleuromutilin class of antibiotics. Our results show that tiamulin is located within the peptidyl transferase center (PTC) of the 50S ribosomal subunit with its tricyclic mutilin core positioned in a tight pocket at the A‐tRNA binding site. Also, the extension, which protrudes from its mutilin core, partially overlaps with the P‐tRNA binding site. Thereby, tiamulin directly inhibits peptide bond formation. Comparison of the tiamulin binding site with other PTC targeting drugs, like chloramphenicol, clindamycin and streptogramins, may facilitate the design of modified or hybridized drugs that extend the applicability of this class of antibiotics.