5exv

Crystal structure of heme binding protein HutX from Vibrio cholerae

spinqualitylabelsall models 5exv, resolution 2.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5exv is a 6 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed HutZ is a cytoplasmic heme-binding protein from Vibrio cholerae. Although we have previously identified HutZ as a heme-degrading enzyme [Uchida, T., et al. (2012) Chem. Commun. 48, 6741-6743], the heme transport protein for HutZ remained unknown. To identify the heme transport protein for HutZ, we focused on the heme utilization operon, hutWXZ. To this end, we constructed an expression system for HutX in Escherichia coli and purified it to homogeneity. An absorption spectral analysis demonstrated that HutX binds heme with a 1:1 stoichiometry and a dissociation constant of 7.4 nM. The crystal structure of HutX displays a fold similar to that of the homologous protein, ChuX, from E. coli O157:H7. A structural comparison of HutX and ChuX, and resonance Raman spectra of heme-HutX, suggest that the axial ligand of the ferric heme is Tyr90. The heme bound to HutX is transferred to HutZ with biphasic dissociation kinetics of 8.3 x 10(-2) and 1.5 x 10(-2) s(-1), values distinctly larger than those for transfer from HutX to apomyoglobin. Surface plasmon resonance experiments confirmed that HutX interacts with HutZ with a dissociation constant of approximately 400 muM. These results suggest that heme is transferred from HutX to HutZ via a specific protein-protein interaction. Therefore, we can conclude that HutX is a cytoplasmic heme transport protein for HutZ. Cytoplasmic Heme-Binding Protein (HutX) from Vibrio cholerae Is an Intracellular Heme Transport Protein for the Heme-Degrading Enzyme, HutZ.,Sekine Y, Tanzawa T, Tanaka Y, Ishimori K, Uchida T Biochemistry. 2016 Feb 16;55(6):884-93. doi: 10.1021/acs.biochem.5b01273. Epub, 2016 Feb 3. PMID:26807477 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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