Crystal structure of rubredoxin from Desulfovibrio gigas to ultra-high 0.68 A resolution
- Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China) and Department of Physics, National Tsing-Hua University, Hsinchu 30043, Taiwan (China)
- Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China)
- Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China) and Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30045, Taiwan (China)
Rubredoxin (D.g. Rd) is a small non-heme iron-sulfur protein shown to function as a redox coupling protein from the sulfate reducing bacteria Desulfovibrio gigas. The protein is generally purified from anaerobic bacteria in which it is thought to be involved in electron transfer or exchange processes. Rd transfers an electron to oxygen to form water as part of a unique electron transfer chain, composed by NADH:rubredoxin oxidoreductase (NRO), rubredoxin and rubredoxin:oxygen oxidoreductase (ROO) in D.g. The crystal structure of D.g. Rd has been determined by means of both a Fe single-wavelength anomalous dispersion (SAD) signal and the direct method, and refined to an ultra-high 0.68 A resolution, using X-ray from a synchrotron. Rd contains one iron atom bound in a tetrahedral coordination by the sulfur atoms of four cysteinyl residues. Hydrophobic and {pi}-{pi} interactions maintain the internal Rd folding. Multiple conformations of the iron-sulfur cluster and amino acid residues are observed and indicate its unique mechanism of electron transfer. Several hydrogen bonds, including N-H..., SG of the iron-sulfur, are revealed clearly in maps of electron density. Abundant waters bound to C-O peptides of residues Val8, Cys9, Gly10, Ala38, and Gly43, which may be involved in electron transfer. This ultrahigh-resolution structure allows us to study in great detail the relationship between structure and function of rubredoxin, such as salt bridges, hydrogen bonds, water structures, cysteine ligands, iron-sulfur cluster, and distributions of electron density among activity sites. For First time, this information will provide a clear role for this protein in a strict anaerobic bacterium.
- OSTI ID:
- 20854512
- Journal Information:
- Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 1 Vol. 349; ISSN 0006-291X; ISSN BBRCA9
- Country of Publication:
- United States
- Language:
- English
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