The nucleotide-binding site of bacterial translation initiation factor 2 (IF2) as a metabolic sensor
| Autor: | Jerneja Tomšic, Cynthia L. Pon, Pohl Milón, Claudio O. Gualerzi, Rolf Boelens, Gert E. Folkers, Enrico Caserta, Mv Rodnina, A La Teana, E Tischenko |
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| Přispěvatelé: | NMR-spectroscopie, Dep Scheikunde, Sub NMR Spectroscopy |
| Rok vydání: | 2006 |
| Předmět: |
Models
Molecular GTP' Stringent response Guanosine Prokaryotic Initiation Factor-2 Guanosine triphosphate Biology Ligands Protein Structure Secondary chemistry.chemical_compound Prokaryotic translation Escherichia coli heterocyclic compounds Binding site Nuclear Magnetic Resonance Biomolecular Binding Sites Multidisciplinary Nucleotides Prokaryotic initiation factor-2 Biological Sciences equipment and supplies Biochemistry chemistry Protein Biosynthesis bacteria Guanosine Triphosphate Alarmone |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America |
| Popis: | Translational initiation factor 2 (IF2) is a guanine nucleotide-binding protein that can bind guanosine 3′,5′-(bis) diphosphate (ppGpp), an alarmone involved in stringent response in bacteria. In cells growing under optimal conditions, the GTP concentration is very high, and that of ppGpp very low. However, under stress conditions, the GTP concentration may decline by as much as 50%, and that of ppGpp can attain levels comparable to those of GTP. Here we show that IF2 binds ppGpp at the same nucleotide-binding site and with similar affinity as GTP. Thus, GTP and the alarmone ppGpp can be considered two alternative physiologically relevant IF2 ligands. ppGpp interferes with IF2-dependent initiation complex formation, severely inhibits initiation dipeptide formation, and blocks the initiation step of translation. Our data suggest that IF2 has the properties of a cellular metabolic sensor and regulator that oscillates between an active GTP-bound form under conditions allowing active protein syntheses and an inactive ppGpp-bound form when shortage of nutrients would be detrimental, if not accompanied by slackening of this synthesis. |
| Databáze: | OpenAIRE |
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