Voici les éléments 1 - 10 sur 68
- PublicationMétadonnées seulementProtein transport in organelles: The Toc complex way of preprotein import(2009)
- PublicationMétadonnées seulementPlastoglobules: versatile lipoprotein particles in plastids(2007)
;Bréhélin, Claire ;van Wijk, Klaas J
- PublicationMétadonnées seulementChloroplast protein import: solve the GTPase riddle for entry(2004)
;Schnell, DannyThe fidelity of the numerous intracellular protein-trafficking pathways to different organelles is dictated by the interactions between the intrinsic targeting signals of substrate proteins and specific receptors that deliver the substrate to the proper organelle. Recent studies of protein targeting to chloroplasts suggest a novel mechanism in which GTP-dependent substrate recognition is coupled to a GTP-driven motor that initiates the translocation of proteins into the organelle.
- PublicationMétadonnées seulementThe targeting of the atToc159 preprotein receptor to the chloroplast outer membrane is mediated by its GTPase domain and is regulated by GTP(2002)
;Smith, Matthew ;Hiltbrunner, Andreas ;Schnell, DannyThe multimeric translocon at the outer envelope membrane of chloroplasts (Toc) initiates the recognition and import of nuclear-encoded preproteins into chloroplasts. Two Toc GTPases, Toc159 and Toc33/34, mediate preprotein recognition and regulate preprotein translocation. Although these two proteins account for the requirement of GTP hydrolysis for import, the functional significance of GTP binding and hydrolysis by either GTPase has not been defined. A recent study indicates that Toc159 is equally distributed between a soluble cytoplasmic form and a membrane-inserted form, raising the possibility that it might cycle between the cytoplasm and chloroplast as a soluble preprotein receptor. In the present study, we examined the mechanism of targeting and insertion of the Arabidopsis thaliana orthologue of Toc159, atToc159, to chloroplasts. Targeting of atToc159 to the outer envelope membrane is strictly dependent only on guanine nucleotides. Although GTP is not required for initial binding, the productive insertion and assembly of atToc159 into the Toc complex requires its intrinsic GTPase activity. Targeting is mediated by direct binding between the GTPase domain of atToc159 and the homologous GTPase domain of atToc33, the Arabidopsis Toc33/34 orthologue. Our findings demonstrate a role for the coordinate action of the Toc GTPases in assembly of the functional Toc complex at the chloroplast outer envelope membrane.
- PublicationMétadonnées seulementEssential role of the G-domain in targeting of the protein import receptor atToc159 to the chloroplast outer membrane(2002)
;Bauer, Jörg ;Hiltbrunner, Andreas ; ;Vidi, Pierre-Alexandre ;Alvarez-Huerta, Mayte ;Smith, Matthew ;Schnell, DannyTwo homologous GTP-binding proteins, atToc33 and atToc159, control access of cytosolic precursor proteins to the chloroplast. atToc33 is a constitutive outer chloroplast membrane protein, whereas the precursor receptor atToc159 also exists in a soluble, cytosolic form. This suggests that atToc159 may be able to switch between a soluble and an integral membrane form. By transient expression of GFP fusion proteins, mutant analysis, and biochemical experimentation, we demonstrate that the GTP-binding domain regulates the targeting of cytosolic atToc159 to the chloroplast and mediates the switch between cytosolic and integral membrane forms. Mutant atToc159, unable to bind GTP, does not reinstate a green phenotype in an albino mutant (ppi2) lacking endogenous atToc159, remaining trapped in the cytosol. Thus, the function of atToc159 in chloroplast biogenesis is dependent on an intrinsic GTP-regulated switch that controls localization of the receptor to the chloroplast envelope.
- PublicationMétadonnées seulementIdentification of two gtp-binding proteins in the chloroplast protein import machinery(1994)
; ;Blobel, Gunter ;Patel, Hitesh ASchnell, DannyTwo of four proteins that associated with translocation intermediates during protein import across the outer chloroplast envelope membrane were identified as guanosine triphosphate (GTP)-binding proteins. Both proteins are integral membrane proteins of the outer chloroplast membrane, and both are partially exposed on the chloroplast surface where they were accessible to thermolysin digestion. Engagement of the outer membrane's import machinery by an import substrate was inhibited by slowly hydrolyzable or non-hydrolyzable GTP analogs. Thus, these GTP-binding proteins may function in protein import into chloroplasts.
- PublicationMétadonnées seulementSTAY-GREEN and chlorophyll catabolic enzymes interact at light-harvesting complex II for chlorophyll detoxification during leaf senescence in Arabidopsis(2012)
;Sakuraba, Yasuhito ;Schelbert, Silvia ;Park, So-Yon ;Han, Su-Hyun ;Lee, Byoung-Doo ;Andrès, Céline Besagni ; ;Hörtensteiner, StefanPaek, Nam-Chon
- PublicationMétadonnées seulementThe PPH1 phosphatase is specifically involved in LHCII dephosphorylation and state transitions in Arabidopsis(2010)
;Shapiguzov, Alexey ;Ingelsson, Björn ;Samol, Iga ; ; ;Rochaix, Jean-David ;Vener, Alexander VGoldschmidt-Clermont, Michel
- PublicationMétadonnées seulementSorting activities in plant cells(2003)
;Eucaryotic cells (plants, animals, fungi, etc.) are subdivided in membrane-bound compartments (organelles), such as the nucleus, mitochondria, chloroplasts, vacuoles, etc. Most organellar proteins are encoded in the nucleus and synthesized in the cytoplasm. Proper sorting of proteins is required to establish and maintain organellar identity. Molecular machineries at the organelle surfaces specifically recognize targeting sequences of their cognate proteins and mediate their translocation across membranes. Proteins destined for the vacuoles are first translocated across the endoplasmic reticulum membrane, packaged into vesicles, transported to the Golgi, where they are sorted into specific vesicles and subsequently carried to the different types of vacuoles. Though plant cells share many features with animal and yeast cells, chloroplasts and distinct lytic and storage vacuoles are unique to plants. Here, we discuss import of proteins into the chloroplast as well as selective sorting of proteins to either the lytic or the storage vacuole.
- PublicationMétadonnées seulement