Identification of Elongation Factor G as the Conserved Cellular Target of Argyrin B

• DOI: 10.1371/journal.pone.0042657
• Publication Date: 2012-09-10T21:08:04Z
• Authors: Beat Nyfeler; Dominic Hoepfner; Deborah Palestrant; Christina A. Kirby; Lewis Whitehead; Robert Yu; Gejing Deng; Ruth E. Caughlan; Angela L. Woods; Adriana K. Jones; S. Whitney Barnes; John R. Walker; Swann Gaulis; Ervan Hauy; Saskia M. Brachmann; Philipp Krastel; Christian Studer; Ralph Riedl; David Estoppey; Thomas Aust; N. Rao Movva; Zuncai Wang; Michael Salcius; Gregory A. Michaud; Gregory McAllister; Leon O. Murphy; John A. Tallarico; Christopher J. Wi...; Charles R. Dean
• Keywords: 0301 basic medicine; Burkholderia; Science; Molecular Sequence Data; Microbial Sensitivity Tests; Saccharomyces cerevisiae; Crystallography, X-Ray; Mitochondrial Proteins; 03 medical and health sciences; Cell Line, Tumor; Animals; Humans; Amino Acid Sequence; Conserved Sequence; Mammals; Sequence Homology, Amino Acid; Q; R; Peptide Elongation Factor G; Pseudomonas aeruginosa; Medicine; Mutant Proteins; Oligopeptides; Allosteric Site; Research Article; Protein Binding

Argyrins, produced by myxobacteria and actinomycetes, are cyclic octapeptides with antibacterial and antitumor activity. Here, we identify elongation factor G (EF-G) as the cellular target of argyrin B in bacteria, via resistant mutant selection and whole genome sequencing, biophysical binding studies and crystallography. Argyrin B binds a novel allosteric pocket in EF-G, distinct from the known EF-G inhibitor antibiotic fusidic acid, revealing a new mode of protein synthesis inhibition. In eukaryotic cells, argyrin B was found to target mitochondrial elongation factor G1 (EF-G1), the closest homologue of bacterial EF-G. By blocking mitochondrial translation, argyrin B depletes electron transport components and inhibits the growth of yeast and tumor cells. Further supporting direct inhibition of EF-G1, expression of an argyrin B-binding deficient EF-G1 L693Q variant partially rescued argyrin B-sensitivity in tumor cells. In summary, we show that argyrin B is an antibacterial and cytotoxic agent that inhibits the evolutionarily conserved target EF-G, blocking protein synthesis in bacteria and mitochondrial translation in yeast and mammalian cells.