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Title: Crystal Structures of Cyclohexanone Monooxygenase Reveal Complex Domain Movements and a Sliding Cofactor

Abstract

Cyclohexanone monooxygenase (CHMO) is a flavoprotein that carries out the archetypical Baeyer-Villiger oxidation of a variety of cyclic ketones into lactones. Using NADPH and O{sub 2} as cosubstrates, the enzyme inserts one atom of oxygen into the substrate in a complex catalytic mechanism that involves the formation of a flavin-peroxide and Criegee intermediate. We present here the atomic structures of CHMO from an environmental Rhodococcus strain bound with FAD and NADP+ in two distinct states, to resolutions of 2.3 and 2.2 {angstrom}. The two conformations reveal domain shifts around multiple linkers and loop movements, involving conserved arginine 329 and tryptophan 492, which effect a translation of the nicotinamide resulting in a sliding cofactor. Consequently, the cofactor is ideally situated and subsequently repositioned during the catalytic cycle to first reduce the flavin and later stabilize formation of the Criegee intermediate. Concurrent movements of a loop adjacent to the active site demonstrate how this protein can effect large changes in the size and shape of the substrate binding pocket to accommodate a diverse range of substrates. Finally, the previously identified BVMO signature sequence is highlighted for its role in coordinating domain movements. Taken together, these structures provide mechanistic insights into CHMO-catalyzed Baeyer-Villigermore » oxidation.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
980113
Report Number(s):
BNL-93031-2010-JA
Journal ID: ISSN 0002-7863; JACSAT; TRN: US201015%%1498
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the American Chemical Society; Journal Volume: 131; Journal Issue: 25
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ARGININE; ATOMS; CRYSTAL STRUCTURE; CYCLOHEXANONE; ENZYMES; ISOALLOXAZINES; KETONES; LACTONES; NADP; NICOTINAMIDE; OXIDATION; OXYGEN; PROTEINS; RANGE; RHODOCOCCUS; SHAPE; SIZE; STRAINS; SUBSTRATES; TRYPTOPHAN; national synchrotron light source

Citation Formats

Mirza, I., Yachnin, B, Wang, S, Grosse, S, Bergeron, H, Imura, A, Iwaki, H, Hasegawa, Y, Lau, P, and Berghuis, A. Crystal Structures of Cyclohexanone Monooxygenase Reveal Complex Domain Movements and a Sliding Cofactor. United States: N. p., 2009. Web. doi:10.1021/ja9010578.
Mirza, I., Yachnin, B, Wang, S, Grosse, S, Bergeron, H, Imura, A, Iwaki, H, Hasegawa, Y, Lau, P, & Berghuis, A. Crystal Structures of Cyclohexanone Monooxygenase Reveal Complex Domain Movements and a Sliding Cofactor. United States. doi:10.1021/ja9010578.
Mirza, I., Yachnin, B, Wang, S, Grosse, S, Bergeron, H, Imura, A, Iwaki, H, Hasegawa, Y, Lau, P, and Berghuis, A. 2009. "Crystal Structures of Cyclohexanone Monooxygenase Reveal Complex Domain Movements and a Sliding Cofactor". United States. doi:10.1021/ja9010578.
@article{osti_980113,
title = {Crystal Structures of Cyclohexanone Monooxygenase Reveal Complex Domain Movements and a Sliding Cofactor},
author = {Mirza, I. and Yachnin, B and Wang, S and Grosse, S and Bergeron, H and Imura, A and Iwaki, H and Hasegawa, Y and Lau, P and Berghuis, A},
abstractNote = {Cyclohexanone monooxygenase (CHMO) is a flavoprotein that carries out the archetypical Baeyer-Villiger oxidation of a variety of cyclic ketones into lactones. Using NADPH and O{sub 2} as cosubstrates, the enzyme inserts one atom of oxygen into the substrate in a complex catalytic mechanism that involves the formation of a flavin-peroxide and Criegee intermediate. We present here the atomic structures of CHMO from an environmental Rhodococcus strain bound with FAD and NADP+ in two distinct states, to resolutions of 2.3 and 2.2 {angstrom}. The two conformations reveal domain shifts around multiple linkers and loop movements, involving conserved arginine 329 and tryptophan 492, which effect a translation of the nicotinamide resulting in a sliding cofactor. Consequently, the cofactor is ideally situated and subsequently repositioned during the catalytic cycle to first reduce the flavin and later stabilize formation of the Criegee intermediate. Concurrent movements of a loop adjacent to the active site demonstrate how this protein can effect large changes in the size and shape of the substrate binding pocket to accommodate a diverse range of substrates. Finally, the previously identified BVMO signature sequence is highlighted for its role in coordinating domain movements. Taken together, these structures provide mechanistic insights into CHMO-catalyzed Baeyer-Villiger oxidation.},
doi = {10.1021/ja9010578},
journal = {Journal of the American Chemical Society},
number = 25,
volume = 131,
place = {United States},
year = 2009,
month = 1
}
  • No abstract prepared.
  • In their efforts to model high-valent intermediates in the oxygen activation cycles of nonheme diiron enzymes such as methane monooxygenase (MMOH-Q) and ribonucleotide reductase (RNR R2-X), the authors have synthesized and spectroscopically characterized a series of bis({mu}-oxo)diiron(III,IV) complexes, [Fe{sub 2}({mu}-O){sub 2}(L){sub 2}](ClO{sub 4}){sub 3}, where L is tris(2-pyridylmethyl)amine (TPA) or its ring-alkylated derivatives. They now report the crystal structure of [Fe{sub 2}({mu}-O){sub 2}(5-Et{sub 3}-TPA){sub 2}](ClO{sub 4}){sub 3} (2), the first example of a structurally characterized reactive iron(IV)-oxo species, which provides accurate metrical parameters for the diamond core structure proposed for this series of complexes. Complex 2 has Fe-{mu}-O distances ofmore » 1.805(3) {angstrom} and 1.860(3) {angstrom}, an Fe-Fe distance of 2.683(1) {angstrom}, and an Fe-{mu}-O-Fe angle of 94.1(1){degree}. The EXAFS spectrum of 2 can be fit well with a combination of four shells: 1 O at 1.82 {angstrom}, 2--3 N at 2.03 {angstrom}, 1 Fe at 2.66 {angstrom}, and 7 C at 2.87 {angstrom}. The distances obtained are in very good agreement with the crystal structure data for 2, though the coordination numbers for the first coordination sphere are underestimated. The EXAFS spectra of MMOH-Q and RNR R2-X contain features that match well with those of 2 (except for the multi-carbon shell at 2.87 {angstrom} arising from pyridyl carbons which are absent in the enzymes), suggesting that an Fe{sub 2}({mu}-O){sub 2} core may be a good candidate for the core structures of the enzyme intermediates. The implications of these studies are discussed.« less
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