5a4i

The mechanism of Hydrogen activation by NiFE-hydrogenases

spinqualitylabelsall models 5a4i, resolution 1.23Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5a4i is a 4 chain structure with sequence from Escherichia coli str. K-12 substr. MC4100. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.23Å Ligands: CL, CSO, FCO, LMT, MG, NI, SF3, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function MBHL_ECOLI This is one of three E.coli hydrogenases synthesized in response to different physiological conditions. HYD1 is believed to have a role in hydrogen cycling during fermentative growth. Publication Abstract from PubMed The active site of [NiFe] hydrogenases contains a strictly conserved arginine that suspends a guanidine nitrogen atom <4.5 A above the nickel and iron atoms. The guanidine headgroup interacts with the side chains of two conserved aspartic acid residues to complete an outer-shell canopy that has thus far proved intractable to investigation by site-directed mutagenesis. Using hydrogenase-1 from Escherichia coli, the strictly conserved residues R509 and D574 have been replaced by lysine (R509K) and asparagine (D574N) and the highly conserved D118 has been replaced by alanine (D118A) or asparagine (D118N/D574N). Each enzyme variant is stable, and their [(RS)2Nimu(SR)2Fe(CO)(CN)2] inner coordination shells are virtually unchanged. The R509K variant had >100-fold lower activity than native enzyme. Conversely, the variants D574N, D118A and D118N/D574N, in which the position of the guanidine headgroup is retained, showed 83%, 26% and 20% activity, respectively. The special kinetic requirement for R509 implicates the suspended guanidine group as the general base in H2 activation by [NiFe] hydrogenases. Mechanism of hydrogen activation by [NiFe] hydrogenases.,Evans RM, Brooke EJ, Wehlin SA, Nomerotskaia E, Sargent F, Carr SB, Phillips SE, Armstrong FA Nat Chem Biol. 2015 Nov 30. doi: 10.1038/nchembio.1976. PMID:26619250 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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