PMID:11795873
| Citation |
Maurizi, MR and Rasulova, F (2002) Degradation of L-glutamate dehydrogenase from Escherichia coli: allosteric regulation of enzyme stability. Arch. Biochem. Biophys. 397:206-16 |
|---|---|
| Abstract |
L-glutamate dehydrogenase (GDH) is stable in exponentially growing Escherichia coli cells but is degraded at a rate of 20-30% per hour in cells starved for either nitrogen or carbon. GDH degradation is energy-dependent, and mutations in ATP-dependent proteases, ClpAP or Lon lead to partial stabilization. Degradation is inhibited by chloramphenicol and is completely blocked in relA mutant cells, suggesting that ribosome-mediated signaling may facilitate GDH degradation. Purified GDH has a single tight site for NADPH binding. Binding of NADPH in the absence of other ligands leads to destabilization of the enzyme. NADPH-induced instability and sensitivity to proteolysis is reversed by tri- and dicarboxylic acids or nucleoside di- and triphosphates. GTP and ppGpp bind to GDH at an allosteric site and reverse the destabilizing effects of NADPH. Native GDH is resistant to degradation by several purified ATP-dependent proteases: ClpAP, ClpXP, Lon, and ClpYQ, but denatured GDH is degraded by ClpAP. Our results suggest that, in vivo, GDH is sensitized to proteases by loss of a stabilizing ligand or interaction with an destabilizing metabolite that accumulates in starving cells, and that any of several ATP-dependent proteases degrade the sensitized protein. |
| Links |
PubMed Online version:10.1006/abbi.2001.2703 |
| Keywords |
ATP-Dependent Proteases; Adenosine Triphosphatases/metabolism; Allosteric Regulation; Ammonia/metabolism; Aspartate Kinase/metabolism; Carboxylic Acids/pharmacology; Chloramphenicol/pharmacology; Cysteine; Endopeptidase Clp; Enzyme Stability; Escherichia coli/enzymology; Escherichia coli Proteins; Glucose/deficiency; Glutamate Dehydrogenase/metabolism; Heat-Shock Proteins/metabolism; Models, Molecular; NADP/metabolism; NADP/pharmacology; NF-kappa B/genetics; NF-kappa B/metabolism; Nucleotides/pharmacology; Phenylmethylsulfonyl Fluoride/pharmacology; Potassium Cyanide/pharmacology; Protease La; Protein Conformation/drug effects; Protein Processing, Post-Translational/drug effects; Serine Endopeptidases/metabolism; Transcription Factor RelA |
| edit table |
Significance
You can help EcoliWiki by summarizing why this paper is useful
Useful Materials and Methods
You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.
Annotations
<annotationlinks/>
EcoliWiki Links
Add links to pages that link here (e.g. gene, product, method pages)
References
See Help:References for how to manage references in EcoliWiki.