1dck

STRUCTURE OF UNPHOSPHORYLATED FIXJ-N COMPLEXED WITH MN2+

spinqualitylabelsall models 1dck, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1dck is a 2 chain structure with sequence from Sinorhizobium meliloti. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: 15P, MN Related: 1d5w, 1dbw, 1dcm Resources: FirstGlance, OCA, RCSB, PDBsum Function [FIXJ_RHIME] FixJ, when activated by FixL, induces the expression of both nifA, required for activation of classical nif and fix genes, and fixK, required for FixN activation. 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 BACKGROUND: Two-component signal transduction pathways are sophisticated phosphorelay cascades widespread in prokaryotes and also found in fungi, molds and plants. FixL/FixJ is a prototypical system responsible for the regulation of nitrogen fixation in the symbiotic bacterium Sinorhizobium meliloti. In microaerobic conditions the membrane-bound kinase FixL uses ATP to transphosphorylate a histidine residue, and the response regulator FixJ transfers the phosphoryl group from the phosphohistidine to one of its own aspartate residues in a Mg(2+)-dependent mechanism. RESULTS: Seven X-ray structures of the unphosphorylated N-terminal receiver domain of FixJ (FixJN) have been solved from two crystal forms soaked in different conditions. Three conformations of the protein were found. In the first case, the protein fold impairs metal binding in the active site and the structure reveals a receiver domain that is self-inhibited for catalysis. In the second conformation, the canonical geometry of the active site is attained, and subsequent metal binding to the protein induces minimal conformational changes. The third conformation illustrates a non-catalytic form of the protein where unwinding of the N terminus of helix alpha 1 has occurred. Interconversion of the canonical and self-inhibited conformations requires a large conformational change of the beta 3-alpha 3 loop region. CONCLUSIONS: These unphosphorylated structures of FixJN stress the importance of flexible peptide segments that delineate the active site. Their movements may act as molecular switches that define the functional status of the protein. Such observations are in line with structural and biochemical results obtained on other response regulator proteins and may illustrate general features that account for the specificity of protein-protein interactions. Structural transitions in the FixJ receiver domain.,Gouet P, Fabry B, Guillet V, Birck C, Mourey L, Kahn D, Samama JP Structure. 1999 Dec 15;7(12):1517-26. PMID:10647182 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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