The Mononuclear Molybdenum Enzymes

Hille, Russ; Hall, James E.; Basu, Partha

doi:10.1021/cr400443z

Cited by 759 publications

(865 citation statements)

References 753 publications

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“…M ost living species require a Mo enzyme (1), and apart from nitrogenase, all of these Mo-containing proteins are part of the large family of "mononuclear Mo" enzymes. The general ability of mononuclear Mo enzymes to catalyze two-electron oxygen atom transfer reactions has been attributed to the Mo(IV)/ Mo(V)/Mo(VI) oxidation state cycling of the active site, and this mechanism is a common part of undergraduate syllabuses (1,2).…”

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confidence: 99%

“…The general ability of mononuclear Mo enzymes to catalyze two-electron oxygen atom transfer reactions has been attributed to the Mo(IV)/ Mo(V)/Mo(VI) oxidation state cycling of the active site, and this mechanism is a common part of undergraduate syllabuses (1,2). Escherichia coli YedY is a mononuclear Mo enzyme (3), and based on sequence homology, the majority of sequenced Gramnegative bacterial genomes encode a YedY-like protein (3)(4)(5).…”

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Electrochemical evidence that pyranopterin redox chemistry controls the catalysis of YedY, a mononuclear Mo enzyme

Adamson

Simonov

Kierzek

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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A long-standing contradiction in the field of mononuclear Mo enzyme research is that small-molecule chemistry on active-site mimic compounds predicts ligand participation in the electron transfer reactions, but biochemical measurements only suggest metal-centered catalytic electron transfer. With the simultaneous measurement of substrate turnover and reversible electron transfer that is provided by Fourier-transformed alternating-current voltammetry, we show that Escherichia coli YedY is a mononuclear Mo enzyme that reconciles this conflict. In YedY, addition of three protons and three electrons to the well-characterized "as-isolated" Mo(V) oxidation state is needed to initiate the catalytic reduction of either dimethyl sulfoxide or trimethylamine N-oxide. Based on comparison with earlier studies and our UV-vis redox titration data, we assign the reversible oneproton and one-electron reduction process centered around +174 mV vs. standard hydrogen electrode at pH 7 to a Mo(V)-to-Mo(IV) conversion but ascribe the two-proton and two-electron transition occurring at negative potential to the organic pyranopterin ligand system. We predict that a dihydro-to-tetrahydro transition is needed to generate the catalytically active state of the enzyme. This is a previously unidentified mechanism, suggested by the structural simplicity of YedY, a protein in which Mo is the only metal site.Fourier-transformed alternating-current voltammetry | mononuclear molybdenum enzyme | protein film electrochemistry | pyranopterin | YedY

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confidence: 99%

mentioning

confidence: 99%

Electrochemical evidence that pyranopterin redox chemistry controls the catalysis of YedY, a mononuclear Mo enzyme

Adamson

Simonov

Kierzek

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…Indeed we can distinguish those belonging to LUCA from those more recently evolved, we can classify them into 3 families according to the modification of the basic form of the molybdenum cofactor and we now know the major steps of their biosynthesis. [2][3][4][5] In the 3 domains of life, molybdoenzymes are essential. Indeed, molybdoenzymes are involved in detoxification processes and in bacterial anaerobic respiration.…”

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confidence: 99%

“…6,7 Among all living organisms, bacteria possess the highest number and diversity of molybdoenzymes. 4 Indeed, even if it is not exhaustive yet, the large panel of enzymatic activity they catalyze make them key players in fundamental geochemical cycles and efficient tools for bioremediation and depollution. [8][9][10][11] In bacteria, among the 3 families of molybdoenzymes (the xanthine oxidase (XO) family, the sulfite oxidase (SO) family and the dimethyl sulfoxide (DMSO) reductase family) only members of the SO family can be matured without the support of auxiliary proteins while molybdoenzymes of the 2 others have been described to require specific accessory proteins dedicated to their biogenesis.…”

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“…The latter point shared by the numerous enzymes of the DMSO reductase family crystallized so far was also observed in solved crystal structures of enzymes of the XO family members. 4,5 The maturation process of enzymes of the XO family has also been well studied, with the xanthine dehydrogenase of Rhodobacter capsulatus as a model. Members of these family are multimeric complexes containing either the basic Mo-MPT or the MCD (molybdopterin cytosine dinucleotide) form of the molybdenum cofactor and also iron sulfur clusters and FAD.…”

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Chaperones in maturation of molybdoenzymes: Why specific is better than general?

et al. 2016

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Molybdoenzymes play essential functions in living organisms and, as a result, in various geochemical cycles. It is thus crucial to understand how these complex proteins become highly efficient enzymes able to perform a wide range of catalytic activities. It has been established that specific chaperones are involved during their maturation process. Here, we raise the question of the involvement of general chaperones acting in concert with dedicated chaperones or not.

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