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Kessler, Félix

Nom
Kessler, Félix
Affiliation principale
Fonction
Professeur.e ordinaire
Email
felix.kessler@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/320
_
0000-0001-6409-5043

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  • Publication
    Accès libre
    atTic110 Is Essential for the Assembly and Function of the Protein Import Machinery of Plastids
    (2005)
    Inaba, Takehito
    ;
    Alvarez-Huerta, Mayte
    ;
    Li, Ming
    ;
    Bauer, Jörg
    ;
    Ewers, Carolin
    ;
    Kessler, Félix 
    ;
    Schnell, Danny J.
  • Publication
    Accès libre
    AtToc90, a New GTP-Binding Component of the Arabidopsis Chloroplast Protein Import Machinery
    (2004)
    Hiltbrunner, Andreas
    ;
    Grünig, Kathrin
    ;
    Alvarez-Huerta, Mayte
    ;
    Infanger, Sibylle
    ;
    Bauer, Jörg
    ;
    Kessler, Félix 
    AtToc159 is a GTP-binding chloroplast protein import receptor. In vivo, atToc159 is required for massive accumulation of photosynthetic proteins during chloroplast biogenesis. Yet, in mutants lacking atToc159 photosynthetic proteins still accumulate, but at strongly reduced levels whereas non-photosynthetic proteins are imported normally: This suggests a role for the homologues of atToc159 (atToc132, -120 and -90). Here, we show that atToc90 supports accumulation of photosynthetic proteins in plastids, but is not required for import of several constitutive proteins. Part of atToc90 associates with the chloroplast surface in vivo and with the Toc-complex core components (atToc75 and atToc33) in vitro suggesting a function in chloroplast protein import similar to that of atToc159. As both proteins specifically contribute to the accumulation of photosynthetic proteins in chloroplasts they may be components of the same import pathway.
  • Publication
    Accès libre
    The major protein import receptor of plastids is essential for chloroplast biogenesis
    (2000)
    Bauer, Jörg
    ;
    Chen, Kunhua
    ;
    Hiltbunner, Andreas
    ;
    Wehrli, Ernst
    ;
    Eugster, Monika
    ;
    Schnell, Danny
    ;
    Kessler, Félix 
    Light triggers the developmental programme in plants that leads to the production of photosynthetically active chloroplasts from non-photosynthetic proplastids1. During this chloroplast biogenesis, the photosynthetic apparatus is rapidly assembled, mostly from nuclear-encoded imported proteins2, 3, 4, which are synthesized in the cytosol as precursors with cleavable amino-terminal targeting sequences called transit sequences. Protein translocon complexes at the outer (Toc complex)5, 6, 7 and inner (Tic complex)6, 8, 9 envelope membranes recognize these transit sequences, leading to the precursors being imported. The Toc complex in the pea consists of three major components, Toc75, Toc34 and Toc159 (formerly termed Toc86)6, 7, 10, 11. Toc159, which is an integral membrane GTPase12, functions as a transit-sequence receptor5, 6, 7, 13. Here we show that Arabidopsis thaliana Toc159 (atToc159) is essential for the biogenesis of chloroplasts. In an Arabidopsis mutant (ppi2) that lacks atToc159, photosynthetic proteins that are normally abundant are transcriptionally repressed, and are found in much smaller amounts in the plastids, although ppi2 does not affect either the expression or the import of less abundant non-photosynthetic plastid proteins. These findings indicate that atToc159 is required for the quantitative import of photosynthetic proteins. Two proteins that are related to atToc159 (atToc120 and atToc132) probably help to maintain basal protein import in ppi2, and so constitute components of alternative, atToc159-independent import pathways.