The mitochondrial ATP synthase of chlorophycean algae contains eight subunits of unknown origin involved in the formation of an atypical stator-stalk and in the dimerization of the complex |
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Authors: | Miriam Vázquez-Acevedo Pierre Cardol Araceli Cano-Estrada Marie Lapaille Claire Remacle Diego González-Halphen |
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Affiliation: | (1) Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-600, Delegación Coyoacán, 04510 México D.F., Mexico;(2) Genetics of Microorganisms, Institute of Plant Biology B22, University of Liège, B-4000 Liège, Belgium |
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Abstract: | Mitochondrial F1F O -ATP synthase of Chlamydomonas reinhardtii and Polytomella sp. is a dimer of 1,600,000 Da. In Chlamydomonas the enzyme lacks the classical subunits that constitute the peripheral stator-stalk as well as those involved in the dimerization of the fungal and mammal complex. Instead, it contains eight novel polypeptides named ASA1 to 8. We show that homologs of these subunits are also present in the chlorophycean algae Polytomella sp. and Volvox carterii. Blue Native Gel Electrophoresis analysis of mitochondria from different green algal species also indicates that stable dimeric mitochondrial ATP synthases may be characteristic of all Chlorophyceae. One additional subunit, ASA9, was identified in the purified mitochondrial ATP synthase of Polytomella sp. The dissociation profile of the Polytomella enzyme at high-temperatures and cross-linking experiments finally suggest that some of the ASA polypeptides constitute a stator-stalk with a unique architecture, while others may be involved in the formation of a highly-stable dimeric complex. The algal enzyme seems to have modified the structural features of its surrounding scaffold, while conserving almost intact the structure of its catalytic subunits. |
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Keywords: | Oxidative phosphorylation F1F O -ATP synthase Dimeric mitochondrial complex V Chlorophycean algae Stator-stalk Chlamydomonas reinhardtii Volvox carterii Polytomella sp ASA subunits |
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