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Structure of reduced DsbA from Escherichia coli in solution
H J Schirra1, C Renner, M Czisch
1Max-Planck-Institut für Biochemie, Am Klopferspitz 18a, D-82152 Martinsried, Germany.
Biochemistry
|June 13, 1998
Summary
The three-dimensional structure of reduced DsbA protein from Escherichia coli was determined using NMR spectroscopy. Structural differences between reduced and oxidized DsbA may facilitate protein folding in bacteria.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biology
Background:
- DsbA is a crucial enzyme for disulfide bond formation in the bacterial periplasm.
- Understanding DsbA's structure is key to elucidating its role in protein folding.
Purpose of the Study:
- To determine the three-dimensional structure of reduced DsbA in aqueous solution.
- To compare the solution structure of reduced DsbA with its crystal structure in the oxidized state.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy was employed to determine the structure.
- Structure calculations utilized simulated annealing with X-PLOR, incorporating distance and dihedral angle constraints.
Main Results:
- The solution structure of reduced DsbA reveals a two-domain enzyme with a thioredoxin-like fold.
- The reduced and oxidized forms share similarities but differ in domain orientation and active site conformation.
- The active site thiol of Cys30 exhibits a very low pKa due to helix dipole and His32 interactions.
Conclusions:
- Structural variations between reduced and oxidized DsbA likely facilitate the release of oxidized substrates.
- The active site's unique environment contributes to the catalytic efficiency of DsbA in disulfide bond formation.