1idr | pdb_00001idr

CRYSTAL STRUCTURE OF THE TRUNCATED-HEMOGLOBIN-N FROM MYCOBACTERIUM TUBERCULOSIS

spinqualitylabelsall models 1idr, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1idr is a 2 chain structure with sequence from Mycobacterium tuberculosis. The May 2003 RCSB PDB Molecule of the Month feature on Hemoglobin by Shuchismita Dutta and David S. Goodsell is 10.2210/rcsb_pdb/mom_2003_5. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.9Å Ligands: HEM, OXY, PO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TRHBN_MYCTU Binds oxygen cooperatively with very high affinity (P(50) = 0.013 mmHg at 20 degrees Celsius) because of a fast combination (25 microM(-1).s(-1)) and a slow dissociation (0.2 s(-1)) rate. 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 Macrophage-generated oxygen- and nitrogen-reactive species control the development of Mycobacterium tuberculosis infection in the host. Mycobacterium tuberculosis 'truncated hemoglobin' N (trHbN) has been related to nitric oxide (NO) detoxification, in response to macrophage nitrosative stress, during the bacterium latent infection stage. The three-dimensional structure of oxygenated trHbN, solved at 1.9 A resolution, displays the two-over-two alpha-helical sandwich fold recently characterized in two homologous truncated hemoglobins, featuring an extra N-terminal alpha-helix and homodimeric assembly. In the absence of a polar distal E7 residue, the O2 heme ligand is stabilized by two hydrogen bonds to TyrB10(33). Strikingly, ligand diffusion to the heme in trHbN may occur via an apolar tunnel/cavity system extending for approximately 28 A through the protein matrix, connecting the heme distal cavity to two distinct protein surface sites. This unique structural feature appears to be conserved in several homologous truncated hemoglobins. It is proposed that in trHbN, heme Fe/O2 stereochemistry and the protein matrix tunnel may promote O2/NO chemistry in vivo, as a M.tuberculosis defense mechanism against macrophage nitrosative stress. Mycobacterium tuberculosis hemoglobin N displays a protein tunnel suited for O2 diffusion to the heme.,Milani M, Pesce A, Ouellet Y, Ascenzi P, Guertin M, Bolognesi M EMBO J. 2001 Aug 1;20(15):3902-9. PMID:11483493 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Hemoglobin 3D structures

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