3zh0

Functional and structural role of the N-terminal extension in Methanosarcina acetivorans protoglobin

spinqualitylabelsall models 3zh0, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3zh0 is a 4 chain structure with sequence from Methanosarcina acetivorans C2A. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2Å Ligands: FMT, GOL, HEM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q8TLY9_METAC Publication Abstract from PubMed Functional and structural properties of protoglobin from Methanosarcina acetivorans, whose Cys(E20)101 residue was mutated to Ser (MaPgb*), and of mutants missing either the first 20N-terminal amino acids (MaPgb*-DeltaN20 mutant), or the first 33N-terminal amino acids [N-terminal loop of 20 amino acids and a 13-residue Z-helix, preceding the globin fold A-helix; (MaPgb*-DeltaN20Z mutant)] have been investigated. In keeping with the MaPgb*-DeltaN20 mutant crystal structure, here reported at 2.0A resolution, which shows an increased exposure of the haem propionates to the solvent, the analysis of ligand binding kinetics highlights high accessibility of ligands to the haem pocket in ferric MaPgb*-DeltaN20. CO binding to ferrous MaPgb*-DeltaN20 displays a marked biphasic behavior, with a fast binding process close to that observed in MaPgb* and a slow carbonylation process, characterized by a rate-limiting step. Conversely, removal of the first 33 residues induces a substantial perturbation of the overall MaPgb* structure, with loss of alpha-helical content and potential partial collapse of the protein chain. As such, ligand binding kinetics are characterized by very slow rates that are independent of ligand concentration, this being indicative of a high energy barrier for ligand access to the haem, possibly due to localized misfolding. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins. Functional and structural role of the N-terminal extension in Methanosarcina acetivorans protoglobin.,Ciaccio C, Pesce A, Tundo GR, Tilleman L, Bertolacci L, Dewilde S, Moens L, Ascenzi P, Bolognesi M, Nardini M, Coletta M Biochim Biophys Acta. 2013 Feb 25. pii: S1570-9639(13)00089-7. doi:, 10.1016/j.bbapap.2013.02.026. PMID:23485914 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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