6bme

Crystal structure of Chlamydomonas reinhardtii THB4

spinqualitylabelsall models 6bme, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6bme is a 2 chain structure with sequence from Chlre. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: HEM, SO4 Gene: THB4 (CHLRE) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed BACKGROUND: The nuclear genome of Chlamydomonas reinhardtii encodes a dozen hemoglobins of the truncated lineage. Four of these, named THB1-4, contain a single ~130-residue globin unit. THB1, which is cytoplasmic and capable of nitric oxide dioxygenation activity, uses a histidine and a lysine as axial ligands to the heme iron. In the present report, we compared THB2, THB3, and THB4 to THB1 to gain structural and functional insights into algal globins. METHODS: We inspected properties of the globin domains prepared by recombinant means through site-directed mutagenesis, electronic absorption, CD, and NMR spectroscopies, and X-ray crystallography. RESULTS: Recombinant THB3, which lacks the proximal histidine but has a distal histidine, binds heme weakly. NMR data demonstrate that the recombinant domains of THB2 and THB4 coordinate the ferrous heme iron with the proximal histidine and a lysine from the distal helix. An X-ray structure of ferric THB4 confirms lysine coordination. THB1, THB2, and THB4 have reduction potentials between -65 and -100 mV, are capable of nitric oxide dioxygenation, are reduced at different rates by the diaphorase domain of C. reinhardtii nitrate reductase, and show different response to peroxide treatment. CONCLUSIONS: Three single-domain C. reinhardtii hemoglobins use lysine as a distal heme ligand in both Fe(III) and Fe(II) oxidation states. This common feature is likely related to enzymatic activity in the management of reactive oxygen species. GENERAL SIGNIFICANCE: Primary structure analysis of hemoglobins has limited power in the prediction of heme ligation. Experimental determination reveals variations in this essential property across the superfamily. Lysine as a heme iron ligand: A property common to three truncated hemoglobins from Chlamydomonas reinhardtii.,Johnson EA, Russo MM, Nye DB, Schlessman JL, Lecomte JTJ Biochim Biophys Acta Gen Subj. 2018 Dec;1862(12):2660-2673. doi:, 10.1016/j.bbagen.2018.08.009. Epub 2018 Aug 10. PMID:30251657 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Hemoglobin 3D structures

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