1jry

Crystal structure of Arg402Lys mutant flavocytochrome c3 from Shewanella frigidimarina

spinqualitylabelsall models 1jry, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1jry is a 2 chain structure with sequence from Shewanella frigidimarina. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2Å Ligands: FAD, FUM, HEM, NA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function FCCA_SHEFR Flavocytochrome that catalyzes the reduction of fumarate to succinate (PubMed:10978153). Is essential for fumarate respiration during anaerobic growth, acting as the terminal reductase (By similarity). Receives electrons from the membrane-bound tetraheme c-type cytochrome CymA (By similarity). In vitro, can use the artificial electron donor methyl viologen (PubMed:10978153).[UniProtKB:P83223][UniProtKB:Q07WU7] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed There is now overwhelming evidence supporting a common mechanism for fumarate reduction in the respiratory fumarate reductases. The X-ray structures of substrate-bound forms of these enzymes indicate that the substrate is well positioned to accept a hydride from FAD and a proton from an arginine side chain. Recent work on the enzyme from Shewanella frigidimarina [Doherty, M. K., Pealing, S. L., Miles, C. S., Moysey, R., Taylor, P., Walkinshaw, M. D., Reid, G. A., and Chapman, S. K. (2000) Biochemistry 39, 10695-10701] has strengthened the assignment of an arginine (Arg402) as the proton donor in fumarate reduction. Here we describe the crystallographic and kinetic analyses of the R402A, R402K, and R402Y mutant forms of the Shewanella enzyme. The crystal structure of the R402A mutant (2.0 A resolution) shows it to be virtually identical to the wild-type enzyme, apart from the fact that a water molecule occupies the position previously taken by part of the guanidine group of R402. Although structurally similar to the wild-type enzyme, the R402A mutant is inactive under all the conditions that were studied. This implies that a water molecule, in this position in the active site, cannot function as the proton donor for fumarate reduction. In contrast to the R402A mutation, both the R402K and R402Y mutant enzymes are active. Although this activity was at a very low level (at pH 7.2 some 10(4)-fold lower than that for the wild type), it does imply that both lysine and tyrosine can fulfill the role of an active site proton donor, albeit very poorly. The crystal structures of the R402K and R402Y mutant enzymes (2.0 A resolution) show that distances from the lysine and tyrosine side chains to the nearest carbon atom of fumarate are approximately 3.5 A, clearly permitting proton transfer. The combined results from mutagenesis, crystallographic, and kinetic studies provide formidable evidence that R402 acts as both a Lewis acid (stabilizing the build-up of negative charge upon hydride transfer from FAD to fumarate) and a Bronsted acid (donating the proton to the substrate to complete the formation of succinate). Kinetic and crystallographic analysis of the key active site acid/base arginine in a soluble fumarate reductase.,Mowat CG, Moysey R, Miles CS, Leys D, Doherty MK, Taylor P, Walkinshaw MD, Reid GA, Chapman SK Biochemistry. 2001 Oct 16;40(41):12292-8. PMID:11591148 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Flavocytochrome 3D structures

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