Structure of Allochromatium vinosum DsrC protein
EMSL Project ID
2319
Abstract
Project Description: The dsrC gene codes for the 12.7 kDa protein DsrC, also known as the gamma subunit of dissimilatory sulfite reductase, and occurs in all sulfate-reducing bacteria (e.g. Desulfovibrio species) and in many other microorganisms . Because DsrC copurifies with the alpha/beta tetramer of dissimilatory sulfite reductase, it is called the gamma subunit, although its actual function is not known. Dissimilatory sulfite reductase is an essential enzyme for anaerobic respiration in sulfate-reducing bacteria. With NMR time allocated previously, we determined the structure of DsrC from the hyperthermophilic archaebacterium Pyrobaculum aerophilum (see progress summary, below), and developed several hypotheses concerning its function. First, we suggest that a portion of the structure which adopts the helix-turn-helix motif may be a DNA binding domain and that DsrC thus may regulate some aspect of expression of the alpha/beta tetramer of dissimilatory sulfite reductase. Second, we propose that the flexible C-terminus of the protein which contains numerous highly conserved residues including an invariant cysteine may interact with the active site of the alpha/beta tetramer of dissimilatory sulfite reductase, perhaps to sense a particular state of the siroheme or iron-sulfur cluster cofactors in conjunction with its regulatory role. In order to verify that these features are functionally significant, we now propose to determine the structure of DsrC from a second organism, the purple sulfur bacterium Allochromatium vinosum. This protein has 42% sequence identity to DsrC from P. aerophilum.The purple sulfur bacteria are an important class of proteobacteria because of their anoxygenic photosynthetic capability. These organisms play key roles in several ecological settings. In contrast to P. aerophilum, the source organism of our previously determined DsrC structure, A. vinosum is a well-studied microorgansm. Numerous genetic tools have been developed for the study of A. vinosum, so the structure determination of DsrC from this organism could have a substantial impact to future downstream research. In addition, the P. aerophilum DsrC structure that we have determined already can be used for comparative analysis with the A. vinosum DsrC structure that is to be determined, enabling us to learn which putative functionally important structural features are conserved in both proteins.Progress Summary:During a previous allocation of NMR time, we collected the data necessary for determining the structure of P. aerophilum DsrC (Fig. 1). This fold has not been previously observed. A manuscript describing the work has been submitted to the European Journal of Biochemistry. Preliminary Data for DsrC from A. vinosum:We have obtained an expression construct for A. vinosum DsrC from Dr. Christiane Dahl of the University of Bonn, Germany. Dr. Dahl is one of the leading researchers in the world working on A. vinosum. Using this construct we have produced and purified 15N-labeled protein and demonstrated that (1) it can be suitably concentrated for solution NMR studies, (2) it is stable over the course of at least one month, and (3) it yields a well dispersed 1H-15N-HSQC spectrum with uniform peak intensity (Fig. 2). These charactaristics indicate that the structure of A. vinosum DsrC is eminently solvable using solution NMR techniques.
Project Details
Project type
Capability Research
Start Date
2001-10-01
End Date
2002-11-18
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Cort JR, U Selan, A Schulte, F Grimm, MA Kennedy, and C Dahl. 2008. "Allochromatium vinosum DsrC: Solution-State NMR Structure, Redox Properties and Interaction with DsrEFH, a Protein Essential for Purple Sulfur Bacterial Sulfur Oxidation ." Journal of Molecular Biology 382:692-707. doi:10.1016/j.jmb.2008.07.022
Ewing RG, C Liu, and Q Hu. 2012. "Modeling Intragranular Diffusion in Low-Connectivity Granular Media." Water Resources Research 48:Article No. W03518. doi:10.1029/2011WR011407
Grimm F, JR Cort, and C Dahl. 2010. "DsrR, a Novel IscA-like Protein Lacking Iron- and Fe-S-Binding Functions, Involved in the Regulation of Sulfur Oxidation in Allochromatium Vinosum." Journal of Bacteriology 192(6):1652-1661. doi:10.1128/JB.01269-09
Kerisit SN, and C Liu. 2012. "Diffusion and Adsorption of Uranyl Carbonate Species in Nanosized Mineral Fractures." Environmental Science & Technology 46(3):1632-1640.
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