1d5w
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(New page: 200px<br /><applet load="1d5w" size="450" color="white" frame="true" align="right" spinBox="true" caption="1d5w, resolution 2.30Å" /> '''PHOSPHORYLATED FIXJ ...)
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Revision as of 10:54, 20 November 2007
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PHOSPHORYLATED FIXJ RECEIVER DOMAIN
Overview
BACKGROUND: A variety of bacterial adaptative cellular responses to, environmental stimuli are mediated by two-component signal transduction, pathways. In these phosphorelay cascades, histidine kinases, transphosphorylate a conserved aspartate in the receiver domain, a, conserved module in the response regulator superfamily. The main effect of, this phosphorylation is to alter the conformation of the response, regulator in order to modulate its biological function. The response, regulator FixJ displays a typical modular arrangement, with a, phosphorylatable N-terminal receiver domain and a C-terminal DNA-binding, domain. In the symbiotic bacterium Sinorhizobium meliloti, phosphorylation, of this response regulator activates transcription of nitrogen-fixation, genes. RESULTS: The crystal structures of the phosphorylated and of the, unphosphorylated N-terminal receiver domain of FixJ (FixJN) were solved at, 2.3 A and 2.4 A resolution, respectively. They reveal the environment of, the phosphoaspartate in the active site and the specific conformational, changes leading to activation of the response regulator. Phosphorylation, of the conserved aspartate induces major structural changes in the beta, 4-alpha 4 loop, and in the signaling surface alpha 4-beta 5 that mediates, dimerization of the phosphorylated full-length response regulator. A, site-directed mutant at this protein-protein interface decreases the, affinity of the phosphorylated response regulator for the fixK promoter, tenfold. CONCLUSIONS: The cascade of phosphorylation-induced, conformational changes in FixJN illustrates the role of conserved residues, in stabilizing the phosphoryl group in the active site, triggering the, structural transition and achieving the post-phosphorylation signaling, events. We propose that these phosphorylation-induced conformational, changes underly the activation of response regulators in general.
About this Structure
1D5W is a Single protein structure of sequence from Sinorhizobium meliloti with SO4 as ligand. Full crystallographic information is available from OCA.
Reference
Conformational changes induced by phosphorylation of the FixJ receiver domain., Birck C, Mourey L, Gouet P, Fabry B, Schumacher J, Rousseau P, Kahn D, Samama JP, Structure. 1999 Dec 15;7(12):1505-15. PMID:10647181
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