2g5g | pdb_00002g5g

Cofacial heme binding to ChaN of Campylobacter jejuni

spinqualitylabelsall models 2g5g, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2g5g is a 1 chain structure with sequence from Camje. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: HEM NonStd Res: MSE Gene: CJ0177 (CAMJE) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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 Campylobacter jejuni is a leading bacterial cause of food-borne illness in the developed world. Like most pathogens, C. jejuni requires iron that must be acquired from the host environment. Although the iron preference of the food-borne pathogen C. jejuni is not established, this organism possesses heme transport systems to acquire iron. ChaN is an iron-regulated lipoprotein from C. jejuni proposed to be associated with ChaR, an outer-membrane receptor. Mutation of PhuW, a ChaN orthologue in Pseudomonas aeruginosa, compromises growth on heme as a sole iron source. The crystal structure of ChaN, determined to 1.9 A resolution reveals that ChaN is comprised of a large parallel beta-sheet with flanking alpha-helices and a smaller domain consisting of alpha-helices. Unexpectedly, two cofacial heme groups ( approximately 3.5 A apart with an inter-iron distance of 4.4 A) bind in a pocket formed by a dimer of ChaN monomers. Each heme iron is coordinated by a single tyrosine from one monomer, and the propionate groups are hydrogen bonded by a histidine and a lysine from the other monomer. Sequence analyses reveal that these residues are conserved among ChaN homologues from diverse bacterial origins. Electronic absorption and electron paramagnetic resonance (EPR) spectroscopy are consistent with heme binding through tyrosine coordination by ChaN in solution yielding a high-spin heme iron structure in a pH-dependent equilibrium with a low-spin species. Analytical ultracentrifugation demonstrates that apo-ChaN is predominantly monomeric and that dimerization occurs with heme binding such that the stability constant for dimer formation increases by 60-fold. Cofacial heme binding is linked to dimerization by a bacterial heme transport protein.,Chan AC, Lelj-Garolla B, I Rosell F, Pedersen KA, Mauk AG, Murphy ME J Mol Biol. 2006 Oct 6;362(5):1108-19. Epub 2006 Aug 4. PMID:16950397 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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