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18 mai 2018: 1 événement

  • Département Biologie des Génomes

    Vendredi 18 mai 11:00-12:00 - Klaas J. van Wijk - School for Integrative Plant Sciences, section of Plant Biology, Cornell University, Ithaca, NY, USA.

    Chloroplast Protein Homeostasis ; complexities of N-terminal protein maturation, the N-end rule and protease networks

    Résumé : Intra-chloroplast maturation and proteolysis is essential in biogenesis, differentiation and protein homeostasis (proteostasis). However, determinants of chloroplast protein life-time and protease-substrate relationships are poorly understood, even if this is of critical importance for plant life. Protein N-termini are major determinants of protein stability in bacteria, eukaryotes (the N-end rule), and perhaps also in chloroplasts. To better understand chloroplast protein maturation and stability, and to provide a base-line for protein degradation studies, we determined chloroplast protein N-termini using terminal amine isotopic labeling of substrates (TAILS) and mass spectrometry. This showed highly specific N-terminal patterns ; the possibility of a chloroplast N-end rule is discussed. The Clp protease system is the most complex and abundant protease in chloroplasts, and consists of a protease core, several chaperones and adaptors. Structural and functional features of the plastid Clp system in Arabidopsis thaliana will be illustrated though reverse genetics analysis combined with biochemical analysis, X-ray crystallography, as well as large scale quantitative proteomics for loss-of-function mutants. Multiple substrates were identified based on their direct interaction with the ClpS1 adaptor (N-recognin) or screening of different loss-of-function protease mutants ; we discuss the potential role of Clp in fine-tuning chloroplast metabolism. Finally, a chloroplast peptidase network based on co-expression analysis will be presented ; this will help elucidate chloroplast proteolysis cascades and substrate-protease relationships and is currently driving our chloroplast proteostasis research.
    Contact : Carmela GIGLIONE <carmela.giglione i2bc.paris-saclay.fr>

    Lieu : Auditorium - bâtiment 21 - Campus CNRS de Gif-sur-Yvette

    Notes de dernières minutes : kv35@cornell.edu. http://blogs.cornell.edu/vanwijk/

    En savoir plus : Département Biologie des Génomes