Effect of the antibiotic purpuromycin on cell-free protein-synthesizing systems.
Purpuromycin, an antibiotic isolated from the culture broth of Actinoplanes ianthinogenes, which is very active against Gram-positive bacteria and fungi, inhibits protein synthesis in both prokaryotic and eukaryotic cell-free systems. The ID50 was 9 microM with the endogenous mRNA-directed rabbit reticulocyte lysate, 17 microM with a poly(U)-directed system from Escherichia coli and 69 microM with a poly(U)-directed system from Artemia salina cysts. Of the three steps of elongation, purpuromycin does not affect the peptidyl-transferase reaction, inhibits the elongation factor 1 (EF-1) dependent binding of phenylalanyl-tRNA and stimulates the GTP-dependent binding of EF-2. When protein synthesis is stopped by the addition of purpuromycin, the nascent peptide chains are found in the puromycin-reactive P site. The results suggest that the mechanism of action of purpuromycin is similar to that of fusidic acid. Both antibiotics would seem to produce a stable guanine nucleotide-ribosome-EF-2 complex which allows one round of translocation but prevents, because of a common or overlapping ribosomal binding site for the two elongation factors, the subsequent EF-1-dependent binding of aminoacyl-tRNA.
Rambelli
F
F
Dipartimento di Patologia sperimentale dell'Università di Bologna, Italy.
Brigotti
M
M
Zamboni
M
M
Denaro
M
M
Montanaro
L
L
Sperti
S
S
D000818:Animals; D001156:Artemia; D001426:Bacterial Proteins / Q000096:biosynthesis; D002474:Cell-Free System / Q000187:drug effects; D004926:Escherichia coli; D009285:Naphthoquinones / Q000494:pharmacology; D010445:Peptide Elongation Factors / Q000378:metabolism; D014176:Protein Biosynthesis; D011817:Rabbits
D001426:Bacterial Proteins; D009285:Naphthoquinones; D010445:Peptide Elongation Factors; C009115:purpuromycin