1xj2
From Proteopedia
(New page: 200px<br /><applet load="1xj2" size="450" color="white" frame="true" align="right" spinBox="true" caption="1xj2, resolution 2.00Å" /> '''CO-bound structure o...) |
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| - | [[Image:1xj2.gif|left|200px]]<br /><applet load="1xj2" size=" | + | [[Image:1xj2.gif|left|200px]]<br /><applet load="1xj2" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1xj2, resolution 2.00Å" /> | caption="1xj2, resolution 2.00Å" /> | ||
'''CO-bound structure of bjFixLH'''<br /> | '''CO-bound structure of bjFixLH'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Rhizobia directly regulate the expression of genes required for symbiotic | + | Rhizobia directly regulate the expression of genes required for symbiotic nitrogen fixation in response to oxygen concentration via the sensor protein FixL. The N-terminal PAS domain of FixL contains a histidine-coordinated heme and regulates the activity of its effector domain, a C-terminal histidine kinase, in response to binding of oxygen and other ligands at the heme. To further investigate ligand-induced inhibition of FixL, we have determined the crystal structures of the heme domain in both the deoxy state and bound to carbon monoxide, a weak inhibitor of FixL kinase activity. Structures collected at room temperature are presented in each state from two crystallographic space groups at 1.8 and 2 A resolution. These structures reveal displacement of the residues of the H(beta) and I(beta) strands by Leu236 upon CO binding, and this structural change propagates more than 15 A to a region of the structure implicated in signal transduction in PAS proteins. Displacement of residues Ile215, Ile216, and Gly217 in the FG loop is also evident, accompanied by the movement of heme propionate 6 upon change in iron ligation. CO binding increases the temperature factors in the FG loop of the protein and disorders the side chain of Arg206, a conserved residue involved in the FG loop switch mechanism. We relate these results to structural changes in other PAS sensor domains and their involvement in catalytic control. |
==About this Structure== | ==About this Structure== | ||
| - | 1XJ2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bradyrhizobium_japonicum Bradyrhizobium japonicum] with HEM and CMO as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1XJ2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bradyrhizobium_japonicum Bradyrhizobium japonicum] with <scene name='pdbligand=HEM:'>HEM</scene> and <scene name='pdbligand=CMO:'>CMO</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XJ2 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: pas domain; heme; oxygen sensor; carbon monoxide]] | [[Category: pas domain; heme; oxygen sensor; carbon monoxide]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:55:18 2008'' |
Revision as of 13:55, 21 February 2008
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CO-bound structure of bjFixLH
Overview
Rhizobia directly regulate the expression of genes required for symbiotic nitrogen fixation in response to oxygen concentration via the sensor protein FixL. The N-terminal PAS domain of FixL contains a histidine-coordinated heme and regulates the activity of its effector domain, a C-terminal histidine kinase, in response to binding of oxygen and other ligands at the heme. To further investigate ligand-induced inhibition of FixL, we have determined the crystal structures of the heme domain in both the deoxy state and bound to carbon monoxide, a weak inhibitor of FixL kinase activity. Structures collected at room temperature are presented in each state from two crystallographic space groups at 1.8 and 2 A resolution. These structures reveal displacement of the residues of the H(beta) and I(beta) strands by Leu236 upon CO binding, and this structural change propagates more than 15 A to a region of the structure implicated in signal transduction in PAS proteins. Displacement of residues Ile215, Ile216, and Gly217 in the FG loop is also evident, accompanied by the movement of heme propionate 6 upon change in iron ligation. CO binding increases the temperature factors in the FG loop of the protein and disorders the side chain of Arg206, a conserved residue involved in the FG loop switch mechanism. We relate these results to structural changes in other PAS sensor domains and their involvement in catalytic control.
About this Structure
1XJ2 is a Single protein structure of sequence from Bradyrhizobium japonicum with and as ligands. Full crystallographic information is available from OCA.
Reference
Crystal structures of deoxy and CO-bound bjFixLH reveal details of ligand recognition and signaling., Key J, Moffat K, Biochemistry. 2005 Mar 29;44(12):4627-35. PMID:15779889
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