“Bio” catalysis for energy: Enzymes, artificial enzymes and bioinspired catalyst

New technologies for storing solar or electrical energy are crucial for the energetic transition. An attractive scenario consists in the conversion of renewable energies into chemical energy, via water splitting into hydrogen and oxygen. Hydrogenases are the most active molecular catalysts for hydrogen production and uptake on earth and are thus extensively studied with respect to their technological exploitation in order to replace noble metals (such as platinum) within (photo) electrolysers and fuel cells. Because these enzymes suffer from a number of drawbacks, in parallel, bioinspired catalysts and artificial hydrogenases are being extensively developed. Here we present our efforts in: (i) engineering hydrogenases and their maturases; (ii) developing bioinspired molecular cobalt-, iron-, molybdenum and nickel-based molecular catalysts; (ii) developing bioinspired heterogeneous electrode materials for water splitting; (iii) developing artificial systems based on the combination of molecular complexes with well-designed protein scaffolds. References: - Biomimetic assembly and activation of [FeFe]-hydrogenases G. Berggren, A. Adamska, C. Lambertz, T. Simmons, J. Esselborn, M. Atta, S. Gambarelli, JM Mouesca, E. Reijerse, W. Lubitz, T. Happe, V.Artero, M. Fontecave Nature 2013, 499, 66-70. - Spontaneous activation of [FeFe]-hydrogenases by an inorganic [2Fe] active site mimic J. Esselborn, C. Lambertz, A. Adamska, T. Simmons, G. Berggren, J. Noth, J. Siebel, A. Hemschemeier, V. Artero, E. Reijerse, M. Fontecave, W. Lubitz, T. Happe Nature Chem. Biol. 2013, 9, 607-609 - Artificial hydrogenases: biohybrid and supramolecular systems for catalytic hydrogen production or uptake G. Caserta, S. Roy, M. Atta, V. Artero, M. Fontecave Curr. Op. Chem. Biol. 2015, 25, 36–47 - Mimicking Hydrogenases: from Biomimetics to Artificial Enzymes T. R. Simmons, G. Berggren, M. Bacchi, M. Fontecave, V. Artero Coord. Chem. Rev. 2014, 270-271, 127-150 -A bio-inspired Molybdenum Complex as a Catalyst for the Photo- and Electroreduction of Protons J-P. Porcher, T. Fogeron, M. Gomez-Mingot, E. Derat, L-M. Chamoreau, Y. Li, M. Fontecave Angew. Chem. Int. Ed. 2015, 54, 14090-14093 - Artificial Hydrogenases based on Cobaloximes and Heme Oxygenase M. Bacchi, E. Veinberg, M. J. Field, J. Niklas, O. G. Poluektov, M. Ikeda-Saito, M. Fontecave, V. Artero ChemPlusChem 2016, 81, 1083-1089 - Chemical assembly of multiple cofactors: the heterologously expressed multidomain [FeFe]-hydrogenase from Megasphaera elsdenii. G. Caserta, A. Adamska-Venkatesh, L. Pecqueur, M. Atta, V. Artero, R. Souvik, E. Reijerse, W. Lubitz, M. Fontecave Biochim. Biophys. Acta, Bioenergetics 2016, 1857, 1734-1740 - The [FeFe]-hydrogenase maturation protein HydF : Structural and Functional Characterization G. Caserta, L. Pecqueur, A. Adamska-Venkatesh, C. Papini, S. Roy, V. Artero, M. Atta, E. Reijerse, W. Lubitz, M. Fontecav

Discovery of superoxide reductase: an historical perspective.

International audienceFor more than 30 years, the only enzymatic system known to catalyze the elimination of superoxide was superoxide dismutase, SOD. SOD has been found in almost all organisms living in the presence of oxygen, including some anaerobic bacteria, supporting the notion that superoxide is a key and general component of oxidative stress. Recently, a new concept in the field of the mechanisms of cellular defense against superoxide has emerged. It was discovered that elimination of superoxide in some anaerobic and microaerophilic bacteria could occur by reduction, a reaction catalyzed by a small metalloenzyme thus named superoxide reductase, SOR. Having played a major role in this discovery, we describe here how the concept of superoxide reduction emerged and how it was experimentally substantiated independently in our laboratory

Mechanism and substrate specificity of the flavin reductase ActVB from Streptomyces coelicolor.

International audienceActVB is the NADH:flavin oxidoreductase participating in the last step of actinorhodin synthesis in Streptomyces coelicolor. It is the prototype of a whole class of flavin reductases with both sequence and functional similarities. The mechanism of reduction of free flavins by ActVB has been studied. Although ActVB was isolated with FMN bound, we have demonstrated that it is not a flavoprotein. Instead, ActVB contains only one flavin binding site, suitable for the flavin reductase activity and with a high affinity for FMN. In addition, ActVB proceeds by an ordered sequential mechanism, where NADH is the first substrate. Whereas ActVB is highly specific for NADH, it is able to catalyze the reduction of a great variety of natural and synthetic flavins, but with K(m) values ranging from 1 microm (FMN) to 69 microm (lumiflavin). We show that both the ribitol-phosphate chain and the isoalloxazine ring contribute to the protein-flavin interaction. Such properties are unique and set the ActVB family apart from the well characterized Fre flavin reductase family

New Light on Methylthiolation Reactions

A novel enzyme, named RimO for ribosomal modification (Anton et al., 2008) catalyzes the methylthiolation of aspartate 88 of the S12 ribosomal protein in Escherichia coli and shows a strong similarity with the iron-sulfur enzyme MiaB involved in the methylthiolation of tRNAs