Mechanism of and exquisite selectivity for O–O bond formation by the heme-dependent chlorite dismutase

Lee, Amanda Q.; Streit, Bennett R.; Zdilla, Michael J.; Abu‐Omar, Mahdi M.; DuBois, Jennifer L.

doi:10.1073/pnas.0804279105

Cited by 81 publications

(165 citation statements)

References 31 publications

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“…The corresponding Trp189 residue from Dechloromonas aromatica Cld has been suggested to generate the electron paramagnetic resonance (EPR)-active tryptophanyl radical appearing from a broad porphyrin π-cation radical signal in a Cld-chlorite mixture. 10 Strikingly, in cytochrome c peroxidase, a tryptophan residue is situated adjacent to the heme propionate, as in Cld. Moreover, based on kinetic data, Cld is predicted to share functional similarities with heme-dependent catalases and peroxidases.…”

Section: Structure Overview and The Active Sitementioning

confidence: 98%

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Crystal Structure of Chlorite Dismutase, a Detoxifying Enzyme Producing Molecular Oxygen

Geus

Thomassen

Hagedoorn

et al. 2009

Journal of Molecular Biology

160

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Section: Structure Overview and The Active Sitementioning

confidence: 98%

“…In this study, highvalent oxo intermediates were characterized by stopped-flow UV-vis spectroscopy. 10 Here, we report the crystal structure of Cld, new insights into the quaternary state of the protein, and structural implications for the proposed catalytic mechanism.…”

Section: Introductionmentioning

confidence: 97%

Crystal Structure of Chlorite Dismutase, a Detoxifying Enzyme Producing Molecular Oxygen

Geus

Thomassen

Hagedoorn

et al. 2009

Journal of Molecular Biology

160

View full text Add to dashboard Cite

“…aromatica RCB in their as-prepared forms at pH 5.0-7.0 are straightforward to explain [8,15,22]. In these Cld, the EPR signal observable at liquid helium temperatures arises from one high-spin Fe 3+ -heme species corresponding to the pentacoordinated ferric ion present in the Cld active site.…”

Section: Influence Of the Purification Protocol In The Cld As-preparementioning

confidence: 98%

The homopentameric chlorite dismutase from Magnetospirillum sp.

Freire

Rivas

Dias

et al. 2015

Journal of Inorganic Biochemistry

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Chlorite dismutase (Cld) is a b-type heme containing enzyme that catalyzes the reduction of chlorite into chloride plus dioxygen. This enzyme has gained attention because it can be used in the development of bioremediation processes, biosensors, and controlled dioxygen production. In the present work, Cld was purified from Magnetospirillum sp. cells cultured anaerobically with acetate/perchlorate until stationary phase. Biochemical, spectroscopic and X-ray crystallography methods showed that Cld from Magnetospirillum sp. is a ~140 kDa homopentamer comprising ~27.8 kDa monomers. Preliminary X-ray crystallography studies confirmed the quaternary structure and the presence of one b-type heme per monomer. The EPR spectroscopic signature of the as-purified Cld samples is affected by the buffer composition used during the purification. Potassium phosphate buffer is the only buffer that affected neither the spectral nor the kinetic properties of Cld. Kinetic studies in solution revealed that Cld from Magnetospirillum sp. decomposes chlorite at high turnover rates with optimal pH6.0. A temperature below 10 °C is required to avoid enzyme inactivation due to cofactor bleaching during turnover, and to achieve full substrate consumption. Cld kinetic parameters were not affected when kinetic assays were performed in the presence of air or under argon atmosphere, but chloride is a weak mixed inhibitor that modifies the EPR signal of as-prepared samples.

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“…Studies of proximal residue mutants of DaCld and NdCld revealed that manipulation of the rigid H-bonding network in Cld significantly weakens binding of haeme b and thereby destabilizes the protein [25][26][27][28][29][30]. In the present work, we studied the effect of disrupting the proximal H-bonding network by comparing wild-type NdCld with the proximal variants E210A and K141E.…”

Section: Introductionmentioning

confidence: 99%

From chlorite dismutase towards HemQ–the role of the proximal H-bonding network in haeme binding

et al. 2016

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SynopsisChlorite dismutase (Cld) and HemQ are structurally and phylogenetically closely related haeme enzymes differing fundamentally in their enzymatic properties. Clds are able to convert chlorite into chloride and dioxygen, whereas HemQ is proposed to be involved in the haeme b synthesis of Gram-positive bacteria. A striking difference between these protein families concerns the proximal haeme cavity architecture. The pronounced H-bonding network in Cld, which includes the proximal ligand histidine and fully conserved glutamate and lysine residues, is missing in HemQ. In order to understand the functional consequences of this clearly evident difference, specific hydrogen bonds in Cld from 'Candidatus Nitrospira defluvii' (NdCld) were disrupted by mutagenesis. The resulting variants (E210A and K141E) were analysed by a broad set of spectroscopic (UV-vis, EPR and resonance Raman), calorimetric and kinetic methods. It is demonstrated that the haeme cavity architecture in these protein families is very susceptible to modification at the proximal site. The observed consequences of such structural variations include a significant decrease in thermal stability and also affinity between haeme b and the protein, a partial collapse of the distal cavity accompanied by an increased percentage of low-spin state for the E210A variant, lowered enzymatic activity concomitant with higher susceptibility to self-inactivation. The high-spin (HS) ligand fluoride is shown to exhibit a stabilizing effect and partially restore wild-type Cld structure and function. The data are discussed with respect to known structure-function relationships of Clds and the proposed function of HemQ as a coprohaeme decarboxylase in the last step of haeme biosynthesis in Firmicutes and Actinobacteria.

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Mechanism of and exquisite selectivity for O–O bond formation by the heme-dependent chlorite dismutase

Abstract: dioxygen ͉ compound I ͉ peroxidase ͉ peroxygenase ͉ chlorite

Cited by 81 publications

References 31 publications

Crystal Structure of Chlorite Dismutase, a Detoxifying Enzyme Producing Molecular Oxygen

Crystal Structure of Chlorite Dismutase, a Detoxifying Enzyme Producing Molecular Oxygen

The homopentameric chlorite dismutase from Magnetospirillum sp.

From chlorite dismutase towards HemQ–the role of the proximal H-bonding network in haeme binding

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