A two-electron-shell game: intermediates of the extradiol-cleaving catechol dioxygenases

Fielding, Andrew J.; Lipscomb, John D.; Que, Lawrence

doi:10.1007/s00775-014-1122-9

Cited by 44 publications

(46 citation statements)

References 54 publications

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“…1. C2,3D are extradiol-cleaving dioxygenases that function by binding both the organic substrate and O 2 at a divalent metal center in the active site (Fielding, Lipscomb, & Que, 2014). X-ray analysis of crystallized C2,3D from P. putida proved a nonheme Fe(II) center in each of the four identical subunits forming the functional enzyme (Kita et al, 1997).…”

Section: Enzymes Of the Meta-ring Cleavage Pathwaysmentioning

confidence: 98%

Catabolism of Phenol and Its Derivatives in Bacteria

Nešvera

Rucká

Pátek

2015

Advances in Applied Microbiology

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Section: Enzymes Of the Meta-ring Cleavage Pathwaysmentioning

confidence: 98%

Catabolism of Phenol and Its Derivatives in Bacteria

Nešvera

Rucká

Pátek

2015

Advances in Applied Microbiology

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“…Cobalt and manganese have been used previously as robust probes to uncover necessary electronic structural properties and structure-activity relationships in other proteins. 33–36 including superoxide dismutase, 37–41 catechol dioxygenase, 42 myoglobin, 43,44 P 1B -type ATPases, 45 and metallothioneins. 46 Understanding the roles of nonheme metal ions beyond the Cu and Fe in native HCO and NOR will provide deeper insights into nature’s choice of metal ion and allow finer control of the activity beyond native enzymes.…”

Section: Introductionmentioning

confidence: 99%

Manganese and Cobalt in the Nonheme-Metal-Binding Site of a Biosynthetic Model of Heme-Copper Oxidase Superfamily Confer Oxidase Activity through Redox-Inactive Mechanism

Reed¹,

Shi

Zhu

et al. 2017

J. Am. Chem. Soc.

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The presence of nonheme metal, such as copper and iron, in the heme-copper oxidase (HCO) superfamily is critical to the enzymatic activity of reducing O2 to H2O, but the exact mechanism the nonheme metal ion uses to confer and fine-tune the activity remains to be understood. We report that manganese and cobalt can bind to the same nonheme site and confer HCO activity in a heme-nonheme biosynthetic model in myoglobin. While the initial rates of O2 reduction by the Mn, Fe and Co derivatives are similar, the percentage of reaction active species formation are 7%, 4% and 1% and the total turnovers are 5.1 ± 1.1, 13.4 ± 0.7, and 82.5 ± 2.5, respectively. These results correlate with the trends of nonheme metal-binding dissociation constants (35 μM, 22 μM and 9 μM) closely, suggesting that tighter metal binding can prevent ROS release from the active site, lessen damage to the protein, and produce higher total turnover numbers. Detailed spectroscopic, electrochemical, and computational studies found no evidence of redox cycling of manganese or cobalt in the enzymatic reactions, and suggest that structural and electronic effects related to the presence of different nonheme metals lead to observed differences in reactivity. This study of the roles of nonheme metal ions beyond the Cu and Fe found in native enzymes has provided deeper insights into nature’s choice of metal ion, and reaction mechanism, and allows for finer control of the enzymatic activity, which is a basis for design of efficient catalysts for oxygen reduction reaction for fuel cells.

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“…15, 17, 18, 32 In the past decade, our laboratories have used a variety of techniques to study the wild-type (WT) enzyme as well as active site variants in which important 2 nd -sphere residues were mutated. 26–30, 33–37 Biochemical studies have shown that His200 serves a variety of critical functions in the activation of dioxygen, among them acid/base catalysis. To further probe the importance of His200, we recently studied a variant, H200C, in which His200 was replaced by cysteine.…”

Section: Introductionmentioning

confidence: 99%

Enzyme Substrate Complex of the H200C Variant of Homoprotocatechuate 2,3-Dioxygenase: Mössbauer and Computational Studies

et al. 2016

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The extradiol, aromatic ring-cleaving enzyme homoprotocatechuate 2,3-dioxygenase (HPCD) catalyzes a complex chain of reactions that involve second sphere residues of the active site. The importance of the 2nd-sphere residue His200 was demonstrated in studies of HPCD variants, such as His200Cys (H200C), which revealed significant retardations of certain steps in the catalytic process as a result of the substitution, allowing novel reaction cycle intermediates to be trapped for spectroscopic characterization. As the H200C variant largely retains the wild-type active site structure and produces the correct ring-cleaved product, this variant presents a valuable target for mechanistic HPCD studies. Here the high-spin FeII states of resting H200C and the H200C–homoprotocatechuate enzyme–substrate (ES) complex have been characterized with Mössbauer spectroscopy to assess the electronic structures of the active site in these states. The analysis reveals a high-spin FeII center in a low symmetry environment that is reflected in the values of the zero-field splitting (ZFS) (D ≈ −8 cm−1, E/D ≈ 1/3 in ES) as well as the relative orientations of the principal axes of the 57Fe magnetic hyperfine (A) and electric field gradient (EFG) tensors relative to the ZFS tensor axes. A spin Hamiltonian analysis of the spectra for the ES complex indicates that the magnetization axis of the integer-spin S = 2 FeII system is nearly parallel to the symmetry axis, z, of the doubly occupied dxy ground orbital deduced from the EFG and A-values, an observation which cannot be rationalized by DFT assisted crystal-field theory. In contrast, ORCA/CASSCF calculations for the ZFS tensor in combination with DFT calculations for the EFG- and A-tensors describe the experimental data remarkably well.

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A two-electron-shell game: intermediates of the extradiol-cleaving catechol dioxygenases

Cited by 44 publications

References 54 publications

Catabolism of Phenol and Its Derivatives in Bacteria

Catabolism of Phenol and Its Derivatives in Bacteria

Manganese and Cobalt in the Nonheme-Metal-Binding Site of a Biosynthetic Model of Heme-Copper Oxidase Superfamily Confer Oxidase Activity through Redox-Inactive Mechanism

Enzyme Substrate Complex of the H200C Variant of Homoprotocatechuate 2,3-Dioxygenase: Mössbauer and Computational Studies

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