Near-neighbor interactions of the membrane-embedded subunits of the mitochondrial ATP synthase of a chlorophycean alga
Por:
Sanchez-Vasquez, Lorenzo, Vazquez-Acevedo, Miriam, de la Mora, Javier, Vega-deLuna, Felix, Cardol, Pierre, Remacle, Claire, Dreyfus, Georges, Gonzalez-Halphen, Diego
Publicada:
1 jul 2017
Resumen:
Mitochondrial F1F0-ATP synthase of the chlorophycean algae Polytomella
sp. can be isolated as a highly stable dimeric complex of 1600 kDa. It
is composed of eight highly conserved orthodox subunits (alpha, beta,
gamma, delta, epsilon, OSCP, a, and c) and nine subunits (Asal-9) that
are exclusive of chlorophycean algae. The Ma subunits replace those that
build up the peripheral stalk and the dimerization domains of the ATP
synthase in other organisms. Little is known about the disposition of
subunits Asa6, Asa8 and Asa9, that are predicted to have transmembrane
stretches and that along with subunit a and a ring of c-subunits, seem
to constitute the membrane-embedded Fo domain of the algal ATP synthase.
Here, we over-expressed and purified the three Asa hydrophobic subunits
and explored their interactions in vitro using a combination of
immunochemical techniques, affinity chromatography, and an in vivo
yeast-two hybrid assays. The results obtained suggest the following
interactions Asa6-Asa6, Asa6-Asa8, Asa6-Asa9, Asa8-Asa8 and Asa8-Asa9.
Cross-linking experiments carried out with the intact enzyme
corroborated some of these interactions. Based on these results, we
propose a model of the disposition of these hydrophobic subunits in the
membrane-embedded sector of the algal ATP synthase. We also propose
based on sequence analysis and hydrophobicity plots, that the algal
subunit a is atypical in as much it lacks the first transmembrane
stretch, exhibiting only four hydrophobic, tilted alpha helices.
Filiaciones:
Sanchez-Vasquez, Lorenzo:
Univ Nacl Autonoma Mexico, Inst Fisiol Celular, Ciudad De Mexico, Mexico
Vazquez-Acevedo, Miriam:
Univ Nacl Autonoma Mexico, Inst Fisiol Celular, Ciudad De Mexico, Mexico
de la Mora, Javier:
Univ Nacl Autonoma Mexico, Inst Fisiol Celular, Ciudad De Mexico, Mexico
Vega-deLuna, Felix:
Univ Nacl Autonoma Mexico, Inst Fisiol Celular, Ciudad De Mexico, Mexico
Cardol, Pierre:
Univ Liege, Genet & Physiol Microalgae, B-4000 Liege, Belgium
Remacle, Claire:
Univ Liege, Genet & Physiol Microalgae, B-4000 Liege, Belgium
Dreyfus, Georges:
Univ Nacl Autonoma Mexico, Inst Fisiol Celular, Ciudad De Mexico, Mexico
Gonzalez-Halphen, Diego:
Univ Nacl Autonoma Mexico, Inst Fisiol Celular, Ciudad De Mexico, Mexico
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