Allosteric Regulation of the Third Ribonucleotide Reductase (NrdEF Enzyme) from Enterobacteriaceae
| Autor: | Rolf Eliasson, Peter Reichard, Albert Jordan, Elisabet Pontis |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
chemistry.chemical_classification
Ribonucleotide biology Allosteric regulation Cell Biology Reductase Biochemistry Molecular biology Enzyme assay Substrate Specificity Ribonucleotide reductase Enzyme Allosteric Regulation Enterobacteriaceae chemistry Ribonucleotide Reductases biology.protein heterocyclic compounds Nucleotide Binding site Molecular Biology |
| Zdroj: | Journal of Biological Chemistry. 271:26582-26587 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.271.43.26582 |
| Popis: | Enterobacteriaceae contain genes for three separate ribonucleotide reductases: nrdAB code for a class Ia enzyme, active during aerobiosis, nrdDG for a class III enzyme, active during anaerobiosis, and nrdEF for a cryptic class Ib enzyme. The NrdEF enzyme provides the active reductase in other, widely different bacteria. Here, we describe the allosteric regulation of the Salmonella typhimurium NrdEF enzyme. It consists of two tightly bound homodimeric proteins, R1E and R2F. Nucleoside triphosphates (ATP, dATP, dGTP, and dTTP) regulate the substrate specificity by binding to a single site of the R1E protein (one nucleotide per polypeptide). Regulation is similar to that of the NrdAB enzyme, with one major exception: dATP stimulates reduction of CDP (and UDP) under conditions when dATP strongly inhibits all activity of the NrdAB enzyme. The nrdA-coded R1 protein contains a second binding site for dATP (and ATP) that controls general enzyme activity. All known R1E proteins lack the 50 N-terminal amino acids of R1, and we propose that the activity site is located in this area of the protein. The more sophisticated regulation of NrdAB enzymes of eukaryotes provides protection against the possibly harmful overproduction of dNTPs. |
| Databáze: | OpenAIRE |
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