Sodium ion cycling mediates energy coupling between complex I and ATP synthase.
We show here sodium ion cycling between complex I from Klebsiella pneumoniae and the F(1)F(0) ATP synthase from Ilyobacter tartaricus in a reconstituted proteoliposome system. In the course of NADH oxidation by complex I, an electrochemical sodium ion gradient was established and served as a driving force for the synthesis of ATP from ADP and phosphate. In the opposite direction, the deltamu(Na(+)) generated by ATP hydrolysis could be coupled to NADH formation by reversed electron transfer from ubiquinol to NAD. For reverse electron transfer, a transmembrane voltage larger than 30 mV was obligatory. No NADH-driven proton transport into the lumen of proteoliposomes was detected. We conclude that Na(+) is used as the exclusive coupling ion by the enterobacterial complex I.
Gemperli
Anja C
AC
Mikrobiologisches Institut der Eidgenössischen Technischen Hochschule, Schmelzbergstrasse 7, CH-8092 Zürich, Switzerland.
Dimroth
Peter
P
Steuber
Julia
J
D000255:Adenosine Triphosphate / Q000378:metabolism; D004563:Electrochemistry; D004583:Electrons; D005673:Fusobacterium / Q000201:enzymology*; D006868:Hydrolysis; D007477:Ions; D007709:Klebsiella / Q000378:metabolism*; D008081:Liposomes; D008954:Models, Biological; D009243:NAD / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D013997:Time Factors
D007477:Ions; D008081:Liposomes; D009243:NAD; D000255:Adenosine Triphosphate; D012964:Sodium; D006180:Proton-Translocating ATPases; D010100:Oxygen