Amphipathic C-terminal region of Escherichia coli NADH dehydrogenase-2 mediates membrane localization |
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Authors: | Villegas Josefina M Volentini Sabrina I Rintoul María R Rapisarda Viviana A |
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Affiliation: | Departamento Bioquímica de la Nutrición, Instituto Superior de Investigaciones Biológicas (Consejo Nacional de Investigaciones Científicas y Técnicas – Universidad Nacional de Tucumán), Chacabuco 461, San Miguel de Tucumán, T4000ILI Tucumán, Argentina;Instituto de Química Biológica “Dr Bernabé Bloj” (Universidad Nacional de Tucumán), Chacabuco 461, San Miguel de Tucumán, T4000ILI Tucumán, Argentina |
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Abstract: | Respiratory NADH dehydrogenase-2 (NDH-2) of Escherichia coli is a membrane-bound flavoprotein. Bioinformatics approaches suggested the involvement of NDH-2 C-terminal region in membrane anchorage. Here, we demonstrated that NDH-2 is a peripheral membrane protein and that its predicted C-terminal amphipathic Arg390-Ala406 helix is sufficient to bind the protein to lipid membranes. Additionally, a cytosolic NDH-2 protein (Trun-3), lacking the last 43 aminoacids, was purified and characterized. FAD cofactor was absent in purified Trun-3. Upon the addition of FAD, Trun-3 maximum velocity was similar to native NDH-2 rate with ferricyanide and MTT acceptors. However, Trun-3 activity was around 5-fold lower with quinones. No significant difference in Km values was observed for both enzymes. For the first time, an active and water soluble NDH-2 was obtained, representing a major improvement for structural/functional characterizations. |
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Keywords: | NADH:quinone oxidoreductase Type 2 NADH dehydrogenase FAD Quinones Membrane proteins Respiratory chain |
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