Structures of the multicomponent Rieske non-heme iron toluene 2,3-dioxygenase enzyme system
Rosmarie Friemann,Kyoung Lee,Kyoung Lee,Eric N. Brown,David T. Gibson,Hans Eklund,S. Ramaswamy +6 more
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TLDR
The crystal structures of the three-component toluene 2,3-dioxygenase system provide a model for electron transfer among bacterial Rieske non-heme iron dioxyGENases.Abstract:
Bacterial Rieske non-heme iron oxygenases catalyze the initial hydroxylation of aromatic hydrocarbon substrates. The structures of all three components of one such system, the toluene 2,3-dioxygenase system, have now been determined. This system consists of a reductase, a ferredoxin and a terminal dioxygenase. The dioxygenase, which was cocrystallized with toluene, is a heterohexamer containing a catalytic and a structural subunit. The catalytic subunit contains a Rieske [2Fe–2S] cluster and mononuclear iron at the active site. This iron is not strongly bound and is easily removed during enzyme purification. The structures of the enzyme with and without mononuclear iron demonstrate that part of the structure is flexible in the absence of iron. The orientation of the toluene substrate in the active site is consistent with the regiospecificity of oxygen incorporation seen in the product formed. The ferredoxin is Rieske type and contains a [2Fe–2S] cluster close to the protein surface. The reductase belongs to the glutathione reductase family of flavoenzymes and consists of three domains: an FAD-binding domain, an NADH-binding domain and a C-terminal domain. A model for electron transfer from NADH via FAD in the reductase and the ferredoxin to the terminal active-site mononuclear iron of the dioxygenase is proposed.read more
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Structural insight into the expanded PCB-degrading abilities of a biphenyl dioxygenase obtained by directed evolution.
Pravindra Kumar,Pravindra Kumar,Mahmood Mohammadi,Jean-François Viger,Diane Barriault,Leticia Gómez-Gil,Lindsay D. Eltis,Jeffrey T. Bolin,Michel Sylvestre +8 more
TL;DR: This study provides important insight about how Rieske-type oxygenases can expand substrate range through mutations that increase the plasticity and/or mobility of protein segments lining the catalytic cavity.
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Structural and Molecular Genetic Analyses of the Bacterial Carbazole Degradation System
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Quaternary Ammonium Oxidative Demethylation: X-ray Crystallographic, Resonance Raman, and UV-Visible Spectroscopic Analysis of a Rieske-Type Demethylase.
Kelly D. Daughtry,Youli Xiao,Deborah Stoner-Ma,Eunsun Cho,Allen M. Orville,Pinghua Liu,Karen N. Allen +6 more
TL;DR: It was demonstrated that the Rieske center was reduced by solvated electrons generated by X-ray photons; the kinetics of the reduction process differed dramatically for the liganded complex compared to unliganded demethylase, which may correspond to the observed turnover in the crystal.
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