title: Transport of Na(+) and K (+) by an antiporter-related subunit from the Escherichia coli NADH dehydrogenase I produced in Saccharomyces cerevisiae.
abstract: The NADH dehydrogenase I from Escherichia coli is a bacterial homolog of the mitochondrial complex I which translocates Na(+) rather than H(+). To elucidate the mechanism of Na(+) transport, the C-terminally truncated NuoL subunit (NuoL(N)) which is related to Na(+)/H(+) antiporters was expressed as a protein A fusion protein (ProtA-NuoL(N)) in the yeast Saccharomyces cerevisiae which lacks an endogenous complex I. The fusion protein inserted into membranes from the endoplasmatic reticulum (ER), as confirmed by differential centrifugation and Western analysis. Membrane vesicles containing ProtA-NuoL(N) catalyzed the uptake of Na(+) and K(+) at rates which were significantly higher than uptake by the control vesicles under identical conditions, demonstrating that ProtA-NuoL(N) translocated Na(+) and K(+) independently from other complex I subunits. Na(+) transport by ProtA-NuoL(N) was inhibited by EIPA (5-(N-ethyl-N-isopropyl)-amiloride) which specifically reacts with Na(+)/H(+) antiporters. The cation selectivity and function of the NuoL subunit as a transporter module of the NADH dehydrogenase complex is discussed.
authors.affiliation: Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.
authors.forename: Anja C
authors.initials: AC
authors.lastname: Gemperli
authors.forename: Christiane
authors.initials: C
authors.lastname: Schaffitzel
authors.forename: Claude
authors.initials: C
authors.lastname: Jakob
authors.forename: Julia
authors.initials: J
authors.lastname: Steuber
mesh_terms: D042967:Electron Transport Complex I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009245:NADH Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D010101:Oxygen Consumption; D011188:Potassium / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D012964:Sodium / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D013205:Staphylococcal Protein A / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D017923:Sodium-Hydrogen Exchangers; D013205:Staphylococcal Protein A; D012964:Sodium; D009245:NADH Dehydrogenase; C479743:NuoL protein, E coli; D042967:Electron Transport Complex I; D011188:Potassium