Modulation of mitochondrial F0F1 catalysis by boundary and bulk phase phospholipids

Isolation and characterization of the mitochondrial ATP synthase from Chlamydomonas reinhardtii. cDNA sequence and deduced protein sequence of the alpha subunit

We have isolated the F0F1-ATP synthase complex from oligomycin-sensitive mitochondria of the green alga Chlamydomonas reinhardtii. A pure and active ATP synthase was obtained by means of sonication, extraction with dodecyl maltoside and ion exchange and gel permeation chromatography in the presence of glycerol, DTT, ATP and PMSF [corrected]. The enzyme consists of 14 subunits as judged by SDS-PAGE. A cDNA clone encoding the ATP synthase alpha subunit has been sequenced. The deduced protein sequence contains a presequence of 45 amino acids which is not present in the mature protein. The mature protein is 58-70% identical to corresponding mitochondrial proteins from other organisms. In contrast to the ATP synthase beta subunit from C. reinhardtii (Franzen and Falk, Plant Mol Biol 19 (1992) 771-780), the protein does not have a C-terminal extension. However, the N-terminal domain of the mature protein is 15-18 residues longer than in ATP synthase alpha subunits from other organisms. Southern blot analysis indicates that the protein is encoded by a single-copy gene.

Large-scale chromatographic purification of F1F0-ATPase and complex I from bovine heart mitochondria

A new chromatographic procedure has been developed for the isolation of F1F0-ATPase and NADH:ubiquinone oxidoreductase (complex I) from a single batch of bovine heart mitochondria. The method employed dodecyl beta-delta-maltoside, a monodisperse, homogeneous detergent in which many respiratory complexes exhibit high activity, for solubilization and subsequent purification by ammonium sulphate fractionation and column chromatography. A combination of anion-exchange, gel-filtration, and dye-ligand affinity chromatography was used to purify both complexes to homogeneity. The F1F0-ATPase preparation contains only the 16 known subunits of the enzyme. It has oligomycin-sensitive ATP hydrolysis activity and, as demonstrated elsewhere, when reconstituted into lipid vesicles it is capable of ATP-dependent proton pumping and of ATP synthesis driven by a proton gradient [Groth and Walker (1996) Biochem. J. 318, 351-357]. The complex I preparation contains all of the subunits identified in other preparations of the enzyme, and has rotenone-sensitive NADH:ubiquinone oxidoreductase and NADH:ferricyanide oxidoreductase activities. The procedure is rapid and reproducible, yielding 50-80 mg of purified F1F0-ATPase and 20-40 mg of purified complex I from 1 g of mitochondrial membranes. Both preparations are devoid of phospholipids, and gel filtration and dynamic light scattering experiments indicate that they are monodisperse. Therefore, the preparations fulfil important prerequisites for structural analysis.

F1F0-ATP synthase from bovine heart mitochondria: development of the purification of a monodisperse oligomycin-sensitive ATPase

A new procedure for the isolation of ATP synthase from bovine mitochondria has been developed, with the primary objective of producing enzyme suitable for crystallization trials. Proteins were extracted from mitochondrial membranes with dodecyl-beta-D-maltoside, and the ATP synthase was purified from the extract in the presence of the same detergent by a combination of ion-exchange and gel-filtration chromatography and ammonium sulphate precipitation. This simple and rapid procedure yields 20-30 mg of highly pure and monodisperse enzyme, evidently consisting of 14 different subunits, amongst them, in apparently stoichiometric amounts with the established subunits, subunit e, a recently discovered subunit of unknown function. The enzyme preparation has an oligomycin-sensitive ATP hydrolysis activity, and so the F1 domain is functionally associated with the membrane domain, F0. In contrast with the N-termini of some of the subunits of bovine mitochondrial F1-ATPase, those of the F1F0-ATP synthase are not degraded by proteolysis during the isolation procedure. This preparation therefore satisfies prerequisites for crystallization trials.