title: The evolution of respiratory O2/NO reductases: an out-of-the-phylogenetic-box perspective.
abstract: Complex life on our planet crucially depends on strong redox disequilibria afforded by the almost ubiquitous presence of highly oxidizing molecular oxygen. However, the history of O2-levels in the atmosphere is complex and prior to the Great Oxidation Event some 2.3 billion years ago, the amount of O2 in the biosphere is considered to have been extremely low as compared with present-day values. Therefore the evolutionary histories of life and of O2-levels are likely intricately intertwined. The obvious biological proxy for inferring the impact of changing O2-levels on life is the evolutionary history of the enzyme allowing organisms to tap into the redox power of molecular oxygen, i.e. the bioenergetic O2 reductases, alias the cytochrome and quinol oxidases. Consequently, molecular phylogenies reconstructed for this enzyme superfamily have been exploited over the last two decades in attempts to elucidate the interlocking between O2 levels in the environment and the evolution of respiratory bioenergetic processes. Although based on strictly identical datasets, these phylogenetic approaches have led to diametrically opposite scenarios with respect to the history of both the enzyme superfamily and molecular oxygen on the Earth. In an effort to overcome the deadlock of molecular phylogeny, we here review presently available structural, functional, palaeogeochemical and thermodynamic information pertinent to the evolution of the superfamily (which notably also encompasses the subfamily of nitric oxide reductases). The scenario which, in our eyes, most closely fits the ensemble of these non-phylogenetic data, sees the low O2-affinity SoxM- (or A-) type enzymes as the most recent evolutionary innovation and the high-affinity O2 reductases (SoxB or B and cbb3 or C) as arising independently from NO-reducing precursor enzymes.
authors: Beadle Center, University of Nebraska-Lincoln, 1901 Vine Street, Lincoln, NE 68588-0660, USA.
authors: Anne-Lise
authors: AL
authors: Ducluzeau
authors: Laboratoire de Bioénergétique et Ingénierie des Protéines UMR 7281 CNRS/AMU, FR3479, Marseille Cedex 20 13402, France.
authors: Barbara
authors: B
authors: Schoepp-Cothenet
authors: Laboratoire de Bioénergétique et Ingénierie des Protéines UMR 7281 CNRS/AMU, FR3479, Marseille Cedex 20 13402, France.
authors: Robert
authors: R
authors: van Lis
authors: Laboratoire de Bioénergétique et Ingénierie des Protéines UMR 7281 CNRS/AMU, FR3479, Marseille Cedex 20 13402, France.
authors: Frauke
authors: F
authors: Baymann
authors: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA.
authors: Michael J
authors: MJ
authors: Russell
authors: Laboratoire de Bioénergétique et Ingénierie des Protéines UMR 7281 CNRS/AMU, FR3479, Marseille Cedex 20 13402, France nitschke@imm.cnrs.fr.
authors: Wolfgang
authors: W
authors: Nitschke
mesh_terms: D001105:Archaea; D001272:Atmosphere; D001419:Bacteria; D001426:Bacterial Proteins / Q000737:chemistry; D005075:Biological Evolution; D016000:Cluster Analysis; D004777:Environment; D019143:Evolution, Molecular; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D010802:Phylogeny; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D010088:Oxidoreductases; C034747:nitric-oxide reductase; D010100:Oxygen
keywords: NO-reductase; O2-reductase; haem–copper oxidase; origin and evolution of respiration; palaeogeochemistry