Energy coupling sites in the electron transport chain of Zymomonas mobilis |
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Authors: | U Kalnenieks N Galinina I Irbe M Toma |
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Institution: | Institute of Microbiology and Biotechnology, Latvian University. A. Kirchenstein street 1, Riga LV-I067, Latvia |
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Abstract: | Abstract Energy-coupling sites in the electron transport chain of the obligately fermentative aerotolerant bacterium Zymomonas mobilis were examined. The H+ /O stoichiometry of the electron transport chain in intact bacteria oxidizing ethanol was close to 3.3. Cytoplasmic membrane vesicles coupled NADH oxidation to ATP synthesis. With ascorbate/phenazine methosulfate they showed oxygen uptake which was sensitive to antimycin A, but no significant ATP synthesis could be detected. Cells with a defective coupling site I, prepared by cultivation on a sulfate-deficient medium, showed a decreased rotenone sensitivity of respiration, and they lacked almost all the respiration-driven proton translocation and ATP synthesis. We conclude that, despite the reported composition of the electron transport chain, only energy coupling site 1 was functional in Z. mobilis . |
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Keywords: | Zymomonas mobilis Oxidative phosphorylation Transmembrane pH gradient Energy-coupling site I H+ / O stoichiometry |
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