Altered regulation of the guanosine 5'-triphosphate activity in a kirromycin-resistant elongation factor Tu.

Abstract

In the preceding article a mutant elongation factor Tu (EF-TuD2216) resistant to the action of kirromycin was found to display a spontaneous guanosine 5'-triphosphatase (GTPase) activity, i.e., in the absence of aminoacyl transfer ribonucleic acid (tRNA) and ribosome-messenger RNA. This is the first example of an Ef-Tu supporting GTPase activity in the absence of macromolecular effectors and/or kirromycin. In this study we show that this activity is elicited by increasing NH4+ concentrations. As additional effect, the mutation caused an increased affinity of EF-Tu for GTP. Ammonium dependence of the GTPase activity an increased affinity for GTP are two properties also found with wild-type EF-Tu in the presence of kirromycin [Fasano, O., Burns, W., Crechet, J.-B., Sander, G., & Parmeggiani, A. (1978) Eur. J. Biochem. 89, 557-565; Sander, G., Okonek, M., Crechet, J.-B., Ivell, R., Bocchini, V., & Parmeggiani, A. (1979) FEBS Lett. 98, 111-114]. Therefore, both binding of kirromycin to wild-type EF-Tu and acquisition of kirromycin resistance introduce functionally related modifications. Kirromycin at high concentrations (0.1 mM) does not interact with mutant EF-TuD2216.GDP but still does with EF-TuD2216.GTP in agreement with our previous finding that EF-Tu.GTP is the preferential target of the antibiotic in the wild type [Fasano, O., Bruns, W., Crechet, J.-B., Sander, G., & Parmeggiani, A. (1978) Eur. J. Biochem. 89, 557-565). The GTPase activity of mutant EF-Tu in the presence of aminoacyl-tRNA and ribosome.mRNA is much higher than with wild-type EF-Tu and also much less dependent on the presence of mRNA. Miscoding for leucine, measured as poly(U)-directed poly(phenyl-alanine/leucine) synthesis at increasing Mg2+ concentrations, is identical for both wild-type and mutant EF-Tu.

• Authors: O Fasano, A Parmeggiani
• Journal: Biochemistry (Biochemistry) Vol. 20 Issue 5 Pg. 1361-6 (Mar 03 1981) ISSN: 0006-2960 [Print] United States
• PMID: 6112013 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Bacterial Agents
• Bacterial Proteins
• Pyridones
• Guanosine Diphosphate
• Ammonia
• Guanosine Triphosphate
• Phosphoric Monoester Hydrolases
• GTP Phosphohydrolases
• Peptide Elongation Factor Tu
• mocimycin

Topics

• Ammonia (pharmacology)
• Anti-Bacterial Agents (pharmacology)
• Bacterial Proteins (metabolism)
• Drug Resistance, Microbial
• Escherichia coli (drug effects, enzymology)
• GTP Phosphohydrolases (metabolism)
• Guanosine Diphosphate (metabolism)
• Guanosine Triphosphate (metabolism)
• Kinetics
• Mutation
• Peptide Elongation Factor Tu
• Phosphoric Monoester Hydrolases (metabolism)
• Pyridones (pharmacology)