1lt0

Crystal structure of the CN-bound BjFixL heme domain

spinqualitylabelsall models 1lt0, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1lt0 is a 1 chain structure with sequence from Bradyrhizobium japonicum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.4Å Ligands: CYN, HEM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function FIXL_BRADU Putative oxygen sensor; modulates the activity of FixJ, a transcriptional activator of nitrogen fixation fixK gene. FixL probably acts as a kinase that phosphorylates FixJ. 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 Structures of the Bradyrhizobium japonicum FixL heme domain have been determined in the absence and presence of specific ligands to elucidate the detailed features of its O2 sensing mechanism. The putative roles of spin-state and steric hindrance were evaluated by the structure determination of ferrous CO-bound BjFixLH and correlating its features with other ligand-bound structures. As found for NO-BjFixLH, no protein conformational change was observed in CO-BjFixLH, suggesting a more complicated mechanism than solely spin state or ligand sterics. To evaluate the role of oxidation state, the structure of the ferrous deoxy-BjFixLH was determined. The structure of deoxy-BjFixLH was found to be virtually identical to the structure of the ferric met-BjFixLH. The role of hydrogen bonding of substrates to a heme-pocket water was evaluated by determining the structure of BjFixLH bound to 1-methyl-imidazole that cannot form a hydrogen bond with this water. In this case, the heme-mediated conformational change was observed, limiting the potential importance of this interaction. Finally, the structure of cyanomet-BjFixLH was revisited to rule out concerns regarding the partial occupancy of the cyanide ligand in a previous structure. In the revised structure, Arg 220 was found to move into the heme pocket to form a hydrogen bond to the bound cyanide ligand. The implications of these results on FixL's sensing mechanism are discussed. Structure-based mechanism of O2 sensing and ligand discrimination by the FixL heme domain of Bradyrhizobium japonicum.,Hao B, Isaza C, Arndt J, Soltis M, Chan MK Biochemistry. 2002 Oct 29;41(43):12952-8. PMID:12390021 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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