title: New insights into the unique structure of the F0F1-ATP synthase from the chlamydomonad algae Polytomella sp. and Chlamydomonas reinhardtii.
abstract: In this study, we investigate the structure of the mitochondrial F(0)F(1)-ATP synthase of the colorless alga Polytomella sp. with respect to the enzyme of its green close relative Chlamydomonas reinhardtii. It is demonstrated that several unique features of the ATP synthase in C. reinhardtii are also present in Polytomella sp. The alpha- and beta-subunits of the ATP synthase from both algae are highly unusual in that they exhibit extensions at their N- and C-terminal ends, respectively. Several subunits of the Polytomella ATP synthase in the range of 9 to 66 kD have homologs in the green alga but do not have known equivalents as yet in mitochondrial ATP synthases of mammals, plants, or fungi. The largest of these so-called ASA (ATP Synthase-Associated) subunits, ASA1, is shown to be an extrinsic protein. Short heat treatment of isolated Polytomella mitochondria unexpectedly dissociated the otherwise highly stable ATP synthase dimer of 1,600 kD into subcomplexes of 800 and 400 kD, assigned as the ATP synthase monomer and F(1)-ATPase, respectively. Whereas no ASA subunits were found in the F(1)-ATPase, all but two were present in the monomer. ASA6 (12 kD) and ASA9 (9 kD), predicted to be membrane bound, were not detected in the monomer and are thus proposed to be involved in the formation or stabilization of the enzyme. A hypothetical configuration of the Chlamydomonad dimeric ATP synthase portraying its unique features is provided to spur further research on this topic.
authors.affiliation: Institut für Biochemie der Pflanzen, Heinrich Heine Universität Düsseldorf, Duesseldorf D-40225, Germany. rvanlis@yahoo.fr
authors.forename: Robert
authors.initials: R
authors.lastname: van Lis
authors.forename: Guillermo
authors.initials: G
authors.lastname: Mendoza-Hernández
authors.forename: Georg
authors.initials: G
authors.lastname: Groth
authors.forename: Ariane
authors.initials: A
authors.lastname: Atteia
mesh_terms: D020418:Algal Proteins / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D006358:Hot Temperature; D008928:Mitochondria / Q000201:enzymology; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D006180:Proton-Translocating ATPases / Q000737:chemistry*
chemical_list: D020418:Algal Proteins; D006180:Proton-Translocating ATPases