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The structure of a reduced mutant T4 glutaredoxin
M Ingelman1, P Nordlund, H Eklund
1Department of Molecular Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
FEBS Letters
|August 21, 1995
Summary
Mutant T4 glutaredoxin crystals show an accessible active site disulfide bond. Dithiotreitol treatment causes minor structural changes, primarily a slight separation of active site cysteines.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Crystallography
Background:
- T4 glutaredoxin is a key enzyme in cellular redox regulation.
- Understanding enzyme structure-function relationships is crucial for biochemical research.
- Mutagenesis studies help elucidate the roles of specific amino acid residues.
Purpose of the Study:
- To investigate the structural consequences of specific mutations in T4 glutaredoxin.
- To determine the accessibility of the active site disulfide bond in a mutant form.
- To analyze the structural impact of dithiotreitol treatment on the mutant enzyme.
Main Methods:
- Site-directed mutagenesis to create T4 glutaredoxin variants (Val15Gly, Tyr16Pro).
- X-ray crystallography to determine the three-dimensional structure of the mutant protein.
- Treatment of protein crystals with dithiotreitol (DTT) and subsequent structural analysis.
Main Results:
- The V15G/Y16P mutant T4 glutaredoxin crystallized with an accessible active site disulfide bond.
- Dithiotreitol treatment induced minimal changes to the overall protein structure.
- Subtle structural alterations were observed around the active site, specifically a slight outward movement of the sulfur atoms in Cys14 and Cys17.
Conclusions:
- The V15G/Y16P mutations in T4 glutaredoxin yield a crystal form with an accessible active site disulfide.
- The active site disulfide in this mutant is conformationally flexible and responsive to reducing agents like DTT.
- These findings provide insights into the structural dynamics of T4 glutaredoxin and its active site.