Functional F1-ATPase Essential in Maintaining Growth and Membrane Potential of Human Mitochondrial DNA-depleted ρ° Cells*
- From the Centre de Génétique Moléculaire et Cellulaire, UMR 5534, CNRS, Université Claude Bernard de Lyon I, 69622 Villeurbanne cedex, France
Abstract
F1-ATPase assembly has been studied in human ρ° cells devoid of mitochondrial DNA (mtDNA). Since, in these cells, oxidative phosphorylation cannot provide ATP, their growth relies on glycolysis. Despite the absence of the mtDNA-coded F0 subunits 6 and 8, ρ° cells possessed normal levels of F1-ATPase α and β subunits. This F1-ATPase was functional and azide- or aurovertin-sensitive but oligomycin-insensitive. In addition, aurovertin decreased cell growth in ρ° cells and also reduced their mitochondrial membrane potential, as measured by rhodamine 123 fluorescence. Therefore, a functional F1-ATPase was important to maintain the mitochondrial membrane potential and the growth of these ρ° cells. Bongkrekic acid, a specific adenine nucleotide translocator (ANT) inhibitor, also reduced ρ° cell growth and mitochondrial membrane potential. In conclusion, ρ° cells need both a functional F1-ATPase and a functional ANT to maintain their mitochondrial membrane potential, which is necessary for their growth. ATP hydrolysis catalyzed by F1 must provide ADP3− at a sufficient rate to maintain a rapid exchange with the glycolytic ATP4− by ANT, this electrogenic exchange inducing a mitochondrial membrane potential efficient enough to sustain cell growth. However, since the effects of bongkrekic acid and of aurovertin were additive, other electrogenic pumps should cooperate with this pathway.
Footnotes
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↵* This work was supported by grants from the CNRS, the French Ministry of Education and Scientific Research (MERS), the Association Française contre les Myopathies (AFM), and the Région Rhône-Alpes.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵‡ Supported by the French Ministry of Education and Scientific Research.
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↵§ To whom correspondence should be addressed. Tel.: 33 04 72 44 83 56; Fax: 33 04 72 44 05 55; E-mail: godinot{at}univ-lyon1.fr.
- Abbreviations:
- ANT
-
adenine nucleotide translocator
- CAPS
-
3-(cyclohexylamino)-1-propanesulfonic acid
- COX II and COX IV
-
subunit II and IV of cytochrome oxidase
- DCCD
-
dicyclohexylcarbodiimide
- FCCP
-
carbonyl cyanidep-trifluoromethoxyphenylhydrazone
- NAO
-
nonyl acridine orange
- R123
-
rhodamine 123
- TBS
-
10 mm Tris-HCl, pH 7.6, 0.1 mm NaCl
- OSCP
-
oligomycin sensitivity conferring protein
- PCR
-
polymerase chain reaction.
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- Received April 9, 1998.
- Revision received June 19, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
