Adaptation of aerobic respiration to low O2 environments
| Autor: | Laura A. Pace, Steven R. Blanke, James Hemp, Fevzi Daldal, Huazhi Han, Robert B. Gennis, Krithika Ganesan, Hanlin Ouyang, Jung Hyeob Roh |
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| Rok vydání: | 2011 |
| Předmět: |
chemistry.chemical_classification
Multidisciplinary biology Proton Bacteria Chemiosmosis Cellular respiration chemistry.chemical_element Reductase Hydrogen-Ion Concentration Proton Pumps Biological Sciences biology.organism_classification Oxygen Adaptation Physiological Aerobiosis Rhodobacter capsulatus Proton pump Biochemistry chemistry Oxidoreductase Biophysics Archaea |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America. 108(34) |
| ISSN: | 1091-6490 |
| Popis: | Aerobic respiration in bacteria, Archaea, and mitochondria is performed by oxygen reductase members of the heme-copper oxidoreductase superfamily. These enzymes are redox-driven proton pumps which conserve part of the free energy released from oxygen reduction to generate a proton motive force. The oxygen reductases can be divided into three main families based on evolutionary and structural analyses (A-, B- and C-families), with the B- and C-families evolving after the A-family. The A-family utilizes two proton input channels to transfer protons for pumping and chemistry, whereas the B- and C-families require only one. Generally, the B- and C-families also have higher apparent oxygen affinities than the A-family. Here we use whole cell proton pumping measurements to demonstrate differential proton pumping efficiencies between representatives of the A-, B-, and C-oxygen reductase families. The A-family has a coupling stoichiometry of 1 H + /e - , whereas the B- and C-families have coupling stoichiometries of 0.5 H + /e - . The differential proton pumping stoichiometries, along with differences in the structures of the proton-conducting channels, place critical constraints on models of the mechanism of proton pumping. Most significantly, it is proposed that the adaptation of aerobic respiration to low oxygen environments resulted in a concomitant reduction in energy conservation efficiency, with important physiological and ecological consequences. |
| Databáze: | OpenAIRE |
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