1H NMR Studies of Mouse Ribonucleotide Reductase: The R2 Protein Carboxyl-Terminal Tail, Essential for Subunit Interaction, Is Highly Flexible but becomes Rigid in the Presence of Protein R1
| Autor: | Astrid Gräslund, Per-Olof Lycksell, Lars Thelander, Davis R, Rolf Ingemarson |
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| Rok vydání: | 1994 |
| Předmět: |
Magnetic Resonance Spectroscopy
Macromolecular Substances Stereochemistry Protein subunit Molecular Sequence Data Biology Biochemistry Mice Ribonucleotide Reductases Escherichia coli Animals Amino Acid Sequence Cloning Molecular Peptide sequence DNA Primers chemistry.chemical_classification Oligopeptide Base Sequence Nuclear magnetic resonance spectroscopy Recombinant Proteins Amino acid Ribonucleotide reductase Enzyme chemistry Chromatography Gel Proton NMR Hydrogen |
| Zdroj: | Biochemistry. 33:2838-2842 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi00176a013 |
| Popis: | Mouse ribonucleotide reductase consists of two nonidentical subunits, proteins R1 and R2, each inactive alone. It has earlier been shown that the carboxyl-terminal part of the R2 protein is essential for subunit association to form the active enzyme complex. We now demonstrate that protein R2 gives rise to a number of sharp 1H NMR resonances, significantly narrower than the major part of the resonances. This line narrowing of certain resonances indicates segmental mobility in the molecule. In two-dimensional 1H TOCSY spectra of protein R2, cross-peak patterns from about 25 amino acid residues are visible. Most of these were assigned to the carboxyl-terminal part of the protein by comparisons with cross-peak patterns of oligopeptides corresponding to the carboxyl terminus of mouse R2 and to the patterns of a seven amino acid residue carboxyl-terminal truncated form of protein R2. These results and the magnitude of the chemical shifts of the assigned residues demonstrate that the carboxyl-terminal part of mouse R2 protein is highly mobile compared to the rest of the protein and essentially unstructured. When protein R1 is added to a solution of protein R2, the sharp resonances are broadened, suggesting that the mobility of the carboxyl-terminal tail of protein R2 is reduced. The possibility of making direct observations of subunit interaction in native and mutagenized R1/R2 proteins should allow discrimination between effects of amino acid replacements on the catalytic mechanism and effects on subunit interaction. |
| Databáze: | OpenAIRE |
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