Effects of the antibiotic pulvomycin on the elongation factor Tu-dependent reactions. Comparison with other antibiotics.
The antibiotic pulvomycin is an inhibitor of protein synthesis that prevents the formation of the ternary complex between elongation factor (EF-) Tu.GTP and aminoacyl-tRNA. In this report, novel aspects of its action on EF-Tu are described. Pulvomycin markedly affects the equilibrium and kinetics of the EF-Tu-nucleotide interaction, particularly of the EF-Tu.GTP complex. The binding affinity of EF-Tu for GTP is increased 1000 times, mainly as the consequence of a dramatic decrease in the dissociation rate of this complex. In contrast, the affinity for GDP is decreased 10-fold due to a marked increase in the dissociation rate of EF-Tu.GDP (25-fold) that mimics the action of EF-Ts, the GDP/GTP exchange factor of EF-Tu. The effects of pulvomycin and EF-Ts can coexist and are simply additive, supporting the conclusion that these two ligands interact with different sites of EF-Tu. This is further confirmed on native PAGE by the ability of EF-Tu to bind the EF-Ts and the antibiotic simultaneously. Pulvomycin enhances the intrinsic EF-Tu GTPase activity, like kirromycin, though to a much more modest extent. As with kirromycin, this stimulation depends on the concentration and nature of the monovalent cations, Li(+) being the most effective one, followed by Na(+), K(+), and NH(4)(+). In the presence of pulvomycin (in contrast to kirromycin), aa-tRNA and/or ribosomes do not enhance the GTPase activity of EF-Tu. The property of pulvomycin to modify selectively the conformation(s) of EF-Tu is also supported by its effect on heat- and urea-dependent denaturation, and tryptic digestion of the protein. Specific differences and similarities between the action of pulvomycin and the other EF-Tu-specific antibiotics are described and discussed.
Anborgh
Pieter H
PH
Groupe de Biophysique-Equipe 2, Ecole Polytechnique, F-91128 Palaiseau Cedex, France.
Okamura
Sumio
S
Parmeggiani
Andrea
A
D000617:Aminoglycosides / Q000737:chemistry* / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D004791:Enzyme Inhibitors / Q000737:chemistry; D004795:Enzyme Stability; D020558:GTP Phosphohydrolases / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006868:Hydrolysis; D010444:Peptide Elongation Factor Tu / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D010445:Peptide Elongation Factors / Q000378:metabolism; D010456:Peptides, Cyclic / Q000737:chemistry* / Q000378:metabolism; D011489:Protein Denaturation; D011728:Pyridones / Q000737:chemistry / Q000378:metabolism; D013844:Thiazoles / Q000737:chemistry / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism; D014508:Urea / Q000737:chemistry
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D010445:Peptide Elongation Factors; D010456:Peptides, Cyclic; D011728:Pyridones; D013844:Thiazoles; C023512:elongation factor Ts; C012521:pulvomycin; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D014508:Urea; D014357:Trypsin; D020558:GTP Phosphohydrolases; D010444:Peptide Elongation Factor Tu; C068122:GE 2270 A; C008536:mocimycin