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Title: Spectroscopic Evidence for a High-Spin Br-Fe(IV)-Oxo Intermediate in the alpha-Ketoglutarate-Dependent Halogenase CytC3 from Streptomyces

Abstract

The complex of the mononuclear non-heme halogenase CytC3 from Streptomyces, Fe(II), {alpha}-ketoglutarate, bromide, and the substrate l-2-aminobutyryl-S-CytC2 reacts with O2 to form a reaction intermediate. Variable-field, freeze-quench Mossbauer spectroscopy reveals this intermediate to be a mixture of two high-spin Fe(IV) complexes in an approximate 3.7/1 ratio. Freeze-quench Fe K-edge X-ray absorption spectroscopy provides further insight into the structure of this intermediate. A short 1.62-Angstroms interaction between the Fe and one of its ligands is attributed to the Fe(IV)-oxo group, and a 2.43-Angstroms interaction is assigned to the Fe-Br interaction. A significantly longer Fe-Br separation (2.53 Angstroms) is observed in the reactant complex, consistent with lower valency of the Fe in the reactant complex. This intermediate is the first example for a Br-Fe(IV)-oxo complex in a protein and provides evidence for a unifying mechanism for Fe(II) and {alpha}-ketoglutarate-dependent dioxygenases and halogenases.

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
959764
Report Number(s):
BNL-82750-2009-JA
Journal ID: ISSN 0002-7863; JACSAT; TRN: US201016%%908
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the American Chemical Society; Journal Volume: 129
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; ABSORPTION SPECTROSCOPY; MIXTURES; PROTEINS; REACTION INTERMEDIATES; SPECTROSCOPY; STREPTOMYCES; SUBSTRATES; national synchrotron light source

Citation Formats

Galonic Fujimori,D., Barr, E., Matthews, M., Koch, G., Yonce, J., Walsh, C., Bollinger, J., Krebs, C., and Riggs-Gelasco, P. Spectroscopic Evidence for a High-Spin Br-Fe(IV)-Oxo Intermediate in the alpha-Ketoglutarate-Dependent Halogenase CytC3 from Streptomyces. United States: N. p., 2007. Web. doi:10.1021/ja076454e.
Galonic Fujimori,D., Barr, E., Matthews, M., Koch, G., Yonce, J., Walsh, C., Bollinger, J., Krebs, C., & Riggs-Gelasco, P. Spectroscopic Evidence for a High-Spin Br-Fe(IV)-Oxo Intermediate in the alpha-Ketoglutarate-Dependent Halogenase CytC3 from Streptomyces. United States. doi:10.1021/ja076454e.
Galonic Fujimori,D., Barr, E., Matthews, M., Koch, G., Yonce, J., Walsh, C., Bollinger, J., Krebs, C., and Riggs-Gelasco, P. Mon . "Spectroscopic Evidence for a High-Spin Br-Fe(IV)-Oxo Intermediate in the alpha-Ketoglutarate-Dependent Halogenase CytC3 from Streptomyces". United States. doi:10.1021/ja076454e.
@article{osti_959764,
title = {Spectroscopic Evidence for a High-Spin Br-Fe(IV)-Oxo Intermediate in the alpha-Ketoglutarate-Dependent Halogenase CytC3 from Streptomyces},
author = {Galonic Fujimori,D. and Barr, E. and Matthews, M. and Koch, G. and Yonce, J. and Walsh, C. and Bollinger, J. and Krebs, C. and Riggs-Gelasco, P.},
abstractNote = {The complex of the mononuclear non-heme halogenase CytC3 from Streptomyces, Fe(II), {alpha}-ketoglutarate, bromide, and the substrate l-2-aminobutyryl-S-CytC2 reacts with O2 to form a reaction intermediate. Variable-field, freeze-quench Mossbauer spectroscopy reveals this intermediate to be a mixture of two high-spin Fe(IV) complexes in an approximate 3.7/1 ratio. Freeze-quench Fe K-edge X-ray absorption spectroscopy provides further insight into the structure of this intermediate. A short 1.62-Angstroms interaction between the Fe and one of its ligands is attributed to the Fe(IV)-oxo group, and a 2.43-Angstroms interaction is assigned to the Fe-Br interaction. A significantly longer Fe-Br separation (2.53 Angstroms) is observed in the reactant complex, consistent with lower valency of the Fe in the reactant complex. This intermediate is the first example for a Br-Fe(IV)-oxo complex in a protein and provides evidence for a unifying mechanism for Fe(II) and {alpha}-ketoglutarate-dependent dioxygenases and halogenases.},
doi = {10.1021/ja076454e},
journal = {Journal of the American Chemical Society},
number = ,
volume = 129,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The complex of the mononuclear non-heme halogenase CytC3 from Streptomyces, Fe(II), {alpha}-ketoglutarate, bromide, and the substrate l-2-aminobutyryl-S-CytC2 reacts with O{sub 2} to form a reaction intermediate. Variable-field, freeze-quench Moessbauer spectroscopy reveals this intermediate to be a mixture of two high-spin Fe(IV) complexes in an approximate 3.7/1 ratio. Freeze-quench Fe K-edge X-ray absorption spectroscopy provides further insight into the structure of this intermediate. A short 1.62-{angstrom} interaction between the Fe and one of its ligands is attributed to the Fe(IV)-oxo group, and a 2.43-{angstrom} interaction is assigned to the Fe-Br interaction. A significantly longer Fe-Br separation (2.53 {angstrom}) is observed inmore » the reactant complex, consistent with lower valency of the Fe in the reactant complex. This intermediate is the first example for a Br-Fe(IV)-oxo complex in a protein and provides evidence for a unifying mechanism for Fe(II) and {alpha}-ketoglutarate-dependent dioxygenases and halogenases.« less
  • No abstract prepared.
  • The dimeric [(FPc)Fe]2({mu}-O) (1) (FPc is the dianion of 1,4,8,11,15,18,22,25-octakis(trifluoromethyl)phthalocyanine) has been shown to transfer its -oxo atom quantitatively to trimethylphosphine and triphenylphosphine. In the case of triphenylphosphine a base such as 1-methylimidazole (MeIm) or pyridine (py) is needed to induce the oxygen atom transfer. The reaction of 1 with MeIm at -40 C and below gives [(MeIm)(FPc)Fe]2({mu}-O) (4), which disproportionates to give (MeIm)2(FPc)Fe (5) and (FPc)Fe=O (6) at higher temperatures. The oxo atom of 6 has been shown to transfer to triphenylphosphine. Similarly, 6 is generated by the disproportionation of 1 with py. It has also been generated bymore » the oxidation of 1 with t-butyl hydroperoxide. [(FPc)Fe]2({mu}-O) catalyzes the oxidation of hydrocarbons by iodosylbenzene. With stilbenes, styrenes, cyclohexenes and butenes as substrates, both epoxidations and alkyl C-H bond oxidations have been observed. The epoxidation of cis-stilbene leads to a mixture of cis- and trans-stilbene oxides, indicating that epoxidation of cis-stilbene, and possibly other olefins as well, proceeds through a non-concerted mechanism.« less
  • The CurA halogenase (Hal) catalyzes a cryptic chlorination leading to cyclopropane ring formation in the synthesis of the natural product curacin A. Hal belongs to a family of enzymes that use Fe{sup 2+}, O{sub 2} and {alpha}-ketoglutarate ({alpha}KG) to perform a variety of halogenation reactions in natural product biosynthesis. Crystal structures of the enzyme in five ligand states reveal strikingly different open and closed conformations dependent on {alpha}KG binding. The open form represents ligand-free enzyme, preventing substrate from entering the active site until both {alpha}KG and chloride are bound, while the closed form represents the holoenzyme with {alpha}KG and chloridemore » coordinated to iron. Candidate amino acid residues involved in substrate recognition were identified by site-directed mutagenesis. These new structures provide direct evidence of a conformational switch driven by {alpha}KG leading to chlorination of an early pathway intermediate.« less
  • Time-resolved resonance Raman spectra have been recorded during the reaction of fully reduced (a{sup 2+}a{sub 3}{sup 2+}) cytochrome oxidase with dioxygen at room temperature. In the spectrum recorded at 800 {mu}s subsequent to carbon monoxide photolysis, a mode is observed at 790 cm{sup {minus}1} that shifts to 755 cm{sup {minus}1} when the experiment is repeated with {sup 18}O{sub 2}. The frequency of this vibration and the magnitude of the {sup 18}O{sub 2} isotopic frequency shift lead the authors to assign the 790-cm{sup {minus}1} mode to the Fe{sup IV}{double bond}O stretching vibration of a ferryl-oxo cytochrome a{sub 3} intermediate that occursmore » in the reaction of fully reduced cytochrome oxidase with dioxygen. The appearance and vibrational frequency of this mode were not affected when D{sub 2}O was used as a solvent. This result suggests that the ferryl-oxo intermediate is not hydrogen bonded. They have also recorded Raman spectra in the high-frequency region during the oxidase/O{sub 2} reaction that show that the oxidation of cytochrome a{sup 2+} is biphasic. These results on the kinetics of the redox activity of cytochrome a are consistent with the branched pathway discussed by Hill et al. for the oxidation of reduced cytochrome oxidase by O{sub 2} at room temperature.« less