1dbw
From Proteopedia
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'''CRYSTAL STRUCTURE OF FIXJ-N''' | '''CRYSTAL STRUCTURE OF FIXJ-N''' | ||
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[[Category: Mourey, L.]] | [[Category: Mourey, L.]] | ||
[[Category: Samama, J P.]] | [[Category: Samama, J P.]] | ||
| - | [[Category: | + | [[Category: Doubly wound five-stranded beta/alpha fold]] |
| - | [[Category: | + | [[Category: Nitrogen fixation regulation]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 13:40:14 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 10:40, 2 May 2008
CRYSTAL STRUCTURE OF FIXJ-N
Overview
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.
About this Structure
1DBW is a Single protein structure of sequence from Sinorhizobium meliloti. Full crystallographic information is available from OCA.
Reference
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 Page seeded by OCA on Fri May 2 13:40:14 2008
