Tagged: Review

The prokaryotic Mo/W-bisPGD enzymes family: A catalytic workhorse in bioenergetic.

Grimaldi S, Schoepp-Cothenet B, Ceccaldi P, Guigliarelli B, Magalon A.

Over the past two decades, prominent importance of molybdenum-containing enzymes in prokaryotes has been put forward by studies originating from different fields. Proteomic or bioinformatic studies underpinned that the list of molybdenum-containing enzymes is far from being complete with to date, more than fifty different enzymes involved in the biogeochemical nitrogen, carbon and sulfur cycles. In particular, the vast majority of prokaryotic molybdenum-containing enzymes belong to the so-called dimethylsulfoxide reductase family. Despite its extraordinary diversity, this family is characterized by the presence of a Mo/W-bis(pyranopterin guanosine dinucleotide) cofactor at the active site. This review highlights what has been learned about the properties of the catalytic site, the modular variation of the structural organization of these enzymes, and their interplay with the isoprenoid quinones. In the last part, this review provides an integrated view of how these enzymes contribute to the bioenergetics of prokaryotes. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems.

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Arsenics as bioenergetic substrates

R. van Lis, W. Nitschke, S. Duval, B. Schoepp-Cothenet

Biochim Biophys Acta. 2013 Feb;1827(2):176-88. doi: 10.1016/j.bbabio.2012.08.007. Epub 2012 Sep 7. Review.

Although at low concentrations, arsenic commonly occurs naturally as a local geological constituent. Whereas both arsenate and arsenite are strongly toxic to life, a number of prokaryotes use these compounds as electron acceptors or donors, respectively, for bioenergetic purposes via respiratory arsenate reductase, arsenite oxidase and alternative arsenite oxidase. The recent burst in discovered arsenite oxidizing and arsenate respiring microbes suggests the arsenic bioenergetic metabolisms to be anything but exotic. The first goal of the present review is to bring to light the widespread distribution and diversity of these metabolizing pathways. The second goal is to present an evolutionary analysis of these diverse energetic pathways. Taking into account not only the available data on the arsenic metabolizing enzymes and their phylogenetical relatives but also the palaeogeochemical records, we propose a crucial role of arsenite oxidation via arsenite oxidase in primordial life. This article is part of a Special Issue entitled: The evolutionary aspects of bioenergetic systems.

The ineluctable requirement for the trans-iron elements molybdenum and/or tungsten in the origin of life.

Schoepp-Cothenet B, van Lis R, Philippot P, Magalon A, Russell MJ, Nitschke W.

Sci Rep. 2012;2:263. doi: 10.1038/srep00263. Epub 2012 Feb 13.

An evolutionary tree of key enzymes from the Complex-Iron-Sulfur-Molybdoenzyme (CISM) superfamily distinguishes “ancient” members, i.e. enzymes present already in the last universal common ancestor (LUCA) of prokaryotes, from more recently evolved subfamilies. The majority of the presented subfamilies and, as a consequence, the Molybdo-enzyme superfamily as a whole, appear to have existed in LUCA. The results are discussed with respect to the nature of bioenergetic substrates available to early life and to problems arising from the low solubility of molybdenum under conditions of the primordial Earth.