Carboxyl group of Glu113 is required for stabilization of the diferrous and bis-Fe(IV) states of MauG.
Carboxyl group of Glu113 is required for stabilization of the diferrous and bis-Fe(IV) states of MauG.
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DOI：
10.1021/bi400905s
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发表时间：
2013-09-17
期刊：
影响因子：
2.9
通讯作者：
Davidson, Victor L.
中科院分区：
文献类型：
--
作者：
Abu Tarboush, Nafez;Yukl, Erik T.;Shin, Sooim;Feng, Manliang;Wilmot, Carrie M.;Davidson, Victor L.
The diheme enzyme MauG catalyzes a six-electron oxidation required for posttranslational modification of a precursor of methylamine dehydrogenase (preMADH) to complete the biosynthesis of its protein-derived tryptophan tryptophylquinone (TTQ) cofactor. Crystallographic studies have implicated Glu113 in the formation of the bis-FeIV state of MauG, in which one heme is FeIV=O and the other is FeIV with His-Tyr axial ligation. An E113Q mutation had no effect on the structure of MauG, but significantly altered its redox properties. E113Q MauG could not be converted to the diferrous state by reduction with dithionite, but was only reduced to a mixed valence FeII/FeIII state, which is never observed in wild-type (WT) MauG. Addition of H2O2 to E113Q MauG generated a high valence state that formed more slowly and was less stable than the bis-FeIV state of WT MauG. E113Q MauG exhibited no detectable TTQ biosynthesis activity in a steady-state assay with preMADH as the substrate. It did catalyze the steady-state oxidation of quinol MADH to the quinone, but 1000-fold less efficiently than WT MauG. Addition of H2O2 to a crystal of the E113Q MauG-preMADH complex resulted in partial synthesis of TTQ. Extended exposure of these crystals to H2O2 resulted in hydroxylation of Pro107 in the distal pocket of the high-spin heme. It is concluded that the loss of the carboxylic group of Glu113 disrupts the redox cooperativity between hemes that allows rapid formation of the diferrous state, and alters the distribution of high-valence species that participate in charge-resonance stabilization of the bis-FeIV redox state.
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DOI：
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发表时间：
2004-12-01
影响因子：
2.2
作者：
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通讯作者：
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影响因子：
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影响因子：
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作者：
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通讯作者：
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DOI：
10.1073/pnas.1109423108
发表时间：
2011-10-11
影响因子：
11.1
作者：
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通讯作者：
Davidson, Victor L.