Journal article
Thioredoxin-insensitive plastid ATP synthase that performs moonlighting functions
Proceedings of the National Academy of Sciences - PNAS, Vol.109(9), pp.3293-3298
02/28/2012
Handle:
https://hdl.handle.net/2376/116174
PMCID: PMC3295299
PMID: 22328157
Abstract
The chloroplast ATP synthase catalyzes the light-driven synthesis of ATP and acts as a key feedback regulatory component of photosynthesis.
Arabidopsis
possesses two homologues of the regulatory γ subunit of the ATP synthase, encoded by the
ATPC1
and
ATPC2
genes. Using a series of mutants, we show that both these subunits can support photosynthetic ATP synthesis in vivo with similar specific activities, but that in wild-type plants, only
γ
1
is involved in ATP synthesis in photosynthesis. The
γ
1
-containing ATP synthase shows classical light-induced redox regulation, whereas the mutant expressing only
γ
2
-ATP synthase (gamma exchange-revised ATP synthase,
gamera
) shows equally high ATP synthase activity in the light and dark. In situ redox titrations demonstrate that the regulatory thiol groups on
γ
2
-ATP synthase remain reduced under physiological conditions but can be oxidized by the strong oxidant diamide, implying that the redox potential for the thiol/disulphide transition in
γ
2
is substantially higher than that for
γ
1
. This regulatory difference may be attributed to alterations in the residues near the redox-active thiols. We propose that
γ
2
-ATP synthase functions to catalyze ATP hydrolysis-driven proton translocation in nonphotosynthetic plastids, maintaining a sufficient transthylakoid proton gradient to drive protein translocation or other processes. Consistent with this interpretation,
ATPC2
is predominantly expressed in the root, whereas modifying its expression results in alteration of root hair development. Phylogenetic analysis suggests that
γ
2
originated from ancient gene duplication, resulting in divergent evolution of functionally distinct ATP synthase complexes in dicots and mosses.
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Details
- Title
- Thioredoxin-insensitive plastid ATP synthase that performs moonlighting functions
- Creators
- Kaori Kohzuma - Plant Research Laboratory, S222 Plant Biology Building, Michigan State University, East Lansing, MI 48824-1312Cristina Dal Bosco - Ludwig-Maximilians-University, Department Biology I, Großhaderner Strasse 2—4, 82152 Planegg-Martinsried, GermanyAtsuko Kanazawa - Plant Research Laboratory, S222 Plant Biology Building, Michigan State University, East Lansing, MI 48824-1312Amit Dhingra - Department of Horticulture, 146 Johnson Hall, Washington State University, Pullman, WA 99164-6340; andWolfgang Nitschke - Laboratoire de Bioénergétique et Ingénierie des Protéines, Centre National de la Recherche Scientifique UPR9036, IFR77, 31 chemin Joseph-Aiguier, 13402 Marseille Cedex 20, FranceJörg Meurer - Ludwig-Maximilians-University, Department Biology I, Großhaderner Strasse 2—4, 82152 Planegg-Martinsried, GermanyDavid M Kramer - Plant Research Laboratory, S222 Plant Biology Building, Michigan State University, East Lansing, MI 48824-1312
- Publication Details
- Proceedings of the National Academy of Sciences - PNAS, Vol.109(9), pp.3293-3298
- Academic Unit
- Horticulture, Department of
- Publisher
- National Academy of Sciences
- Identifiers
- 99900547741101842
- Language
- English
- Resource Type
- Journal article