3k1a | pdb_00003k1a

Insights into substrate binding at FeMo-cofactor in nitrogenase from the structure of an alpha-70Ile MoFe protein variant

spinqualitylabelsall models 3k1a, resolution 2.23Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3k1a is a 4 chain structure with sequence from Azotobacter vinelandii. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.23Å Ligands: CA, HCA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function NIFD_AZOVI This molybdenum-iron protein is part of the nitrogenase complex that catalyzes the key enzymatic reactions in nitrogen fixation. 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 The X-ray crystal structure is presented for a nitrogenase MoFe protein where the alpha subunit residue at position 70 (alpha-70(Val)) has been substituted by the amino acid isoleucine (alpha-70(Ile)). Substitution of alpha-70(Val) by alpha-70(Ile) results in a MoFe protein that is hampered in its ability to reduce a range of substrates including acetylene and N(2), yet retains normal proton reduction activity. The 2.3A structure of the alpha-70(Ile) MoFe protein is compared to the alpha-70(Val) wild-type MoFe protein, revealing that the delta methyl group of alpha-70(Val) is positioned over Fe6 within the active site FeMo-cofactor. This work provides strong crystallographic support for the previously proposed model that substrates bind and are reduced at a single 4Fe-4S face of the FeMo-cofactor and that when alpha-70(Val) is substituted by alpha-70(Ile) access of substrates to Fe6 of this face is effectively blocked. Furthermore the detailed examination of the structure provides the basis for understanding the ability to trap and characterize hydrides in the variant, contributing significantly to our understanding of substrate access and substrate reduction at the FeMo-cofactor active site of nitrogenase. Insights into substrate binding at FeMo-cofactor in nitrogenase from the structure of an alpha-70(Ile) MoFe protein variant.,Sarma R, Barney BM, Keable S, Dean DR, Seefeldt LC, Peters JW J Inorg Biochem. 2010 Apr;104(4):385-9. Epub 2009 Nov 26. PMID:20022118 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Nitrogenase 3D structures

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