1lsv

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Revision as of 18:43, 20 November 2007

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spinqualitylabelsall models 1lsv, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of the CO-bound BjFixL heme domain

Overview

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.

About this Structure

1LSV is a Single protein structure of sequence from Bradyrhizobium japonicum with HEM and CMO as ligands. Full crystallographic information is available from OCA.

Reference

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

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