6e17

A131E mutant of cyt P460 of Nitrosomonas sp. AL212 with NO bound

spinqualitylabelsall models 6e17, resolution 1.97Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6e17 is a 4 chain structure with sequence from Nitrosomonas sp. AL212. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.97Å Ligands: HEC, NO Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function F9ZFJ0_9PROT Publication Abstract from PubMed Ammonia oxidizing bacteria (AOB) use the cytotoxic, energetic molecule hydroxylamine (NH2OH) as a source of reducing equivalents for cellular respiration. Despite disproportionation or violent decomposition being typical outcomes of reactions of NH2OH with iron, AOB and anammox heme P460 proteins including cytochrome (cyt) P460 and hydroxylamine oxidoreductase (HAO) effect controlled, stepwise oxidation of NH2OH to nitric oxide (NO). Curiously, a recently characterized cyt P460 variant from the AOB Nitrosomonas sp. AL212 is able to form all intermediates of cyt P460 catalysis, but is nevertheless incompetent for NH2OH oxidation. We now show via site-directed mutagenesis, activity assays, spectroscopy, and structural biology that this lack of activity is attributable to the absence of a critical basic glutamate residue in the distal pocket above the heme P460 cofactor. This substitution is the only distinguishing characteristic of a protein that is otherwise effectively structurally and spectroscopically identical to an active variant. This highlights and reinforces a fundamental principal of metalloenzymology: metallocofactor inner-sphere geometric and electronic structures are in many cases insufficient for imbuing reactivity; a precisely defined outer coordination sphere contributed by the polypeptide matrix can be the key differentiator between a metalloenzyme and an unreactive metalloprotein. Controlling a burn: outer-sphere gating of hydroxylamine oxidation by a distal base in cytochrome P460.,Smith MA, Majer SH, Vilbert AC, Lancaster KM Chem Sci. 2019 Mar 6;10(13):3756-3764. doi: 10.1039/c9sc00195f. eCollection 2019 , Apr 7. PMID:31015919 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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