Options
Kessler, Félix
Nom
Kessler, Félix
Affiliation principale
Fonction
Professeur.e ordinaire
Email
felix.kessler@unine.ch
Identifiants
Résultat de la recherche
10 Résultats
Voici les éléments 1 - 10 sur 10
- PublicationMétadonnées seulementThe function and diversity of plastid protein import pathways: A multilane GTPase highway into plastids(2006)
; Schnell, DannyThe photosynthetic chloroplast is the hallmark organelle of green plants. During the endosymbiotic evolution of chloroplasts, the vast majority of genes from the original cyanobacterial endosymbiont were transferred to the host cell nucleus. Chloroplast biogenesis therefore requires the import of nucleus-encoded proteins from their site of synthesis in the cytosol. The majority of proteins are imported by the activity of Toc and Tic complexes located within the chloroplast envelope. In addition to chloroplasts, plants have evolved additional, non-photosynthetic plastid types that are essential components of all cells. Recent studies indicate that the biogenesis of various plastid types relies on distinct but homologous Toc-Tic import pathways that have specialized in the import of specific classes of substrates. These different import pathways appear to be necessary to balance the essential physiological role of plastids in cellular metabolism with the demands of cellular differentiation and plant development. - 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 seulementAtTic110 functions as a scaffold for coordinating the stromal events of protein import into chloroplasts(2003)
; Schnell, DannyThe translocon of the inner envelope membrane of chloroplasts ( Tic) mediates the late events in the translocation of nucleus-encoded preproteins into chloroplasts. Tic110 is a major integral membrane component of active Tic complexes and has been proposed to function as a docking site for translocation-associated stromal factors and as a component of the protein-conducting channel. To investigate the various proposed functions of Tic110, we have investigated the structure, topology, and activities of a 97.5-kDa fragment of Arabidopsis Tic110 ( atTic110) lacking only the amino-terminal transmembrane segments. The protein was expressed both in Escherichia coli and Arabidopsis as a stable, soluble protein with a high alpha-helical content. Binding studies demonstrate that a region of the at-Tic110-soluble domain selectively associates with chloroplast preproteins at the late stages of membrane translocation. These data support the hypothesis that the bulk of Tic110 extends into the chloroplast stroma and suggest that the domain forms a docking site for preproteins as they emerge from the Tic translocon. - PublicationMétadonnées seulementA GTPase gate for protein import into chloroplasts(2002)
; Schnell, DannyProtein import into chloroplasts is regulated by the binding and hydrolysis of GTP at two homologous GTPases, Toc34 and Toc159. The crystal structure of the Toc34 GTP-binding domain suggests that GTP-regulated dimerization of the Toc GTPase domains controls the targeting and translocation of preproteins at the chloroplast envelope. - 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)
; 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)
; - PublicationMétadonnées seulementIdentification of proteins associated with plastoglobules isolated from pea (Pisum sativum L.) chloroplasts(1999)
; - PublicationMétadonnées seulementA consensus nomenclature for the protein-import components of the chloroplast envelope(1997)
; - PublicationMétadonnées seulementIsolation of components of the chloroplast protein import machinery(1994)
; Blobel, GunterComponents of the protein import machinery of the chloroplast were isolated by a procedure in which the import machinery was engaged in vitro with a tagged import substrate under conditions that yielded largely chloroplast envelope-bound import intermediates. Subsequent detergent solubilization of envelope membranes showed that six envelope polypeptides copurified specifically and, apparently, stoichiometrically with the import intermediates. Four of these polypeptides are components of the outer membrane import machinery and are associated with early import intermediates. Two of these polypeptides have been characterized. One is a homolog of the heat shock protein hsp70; the other one is a channel-protein candidate. - PublicationMétadonnées seulementIdentification of two gtp-binding proteins in the chloroplast protein import machinery(1994)
;