title: The chloroplast import receptor Toc90 partially restores the accumulation of Toc159 client proteins in the Arabidopsis thaliana ppi2 mutant.
abstract: Successful import of hundreds of nucleus-encoded proteins is essential for chloroplast biogenesis. The import of cytosolic precursor proteins relies on the Toc- (translocon at the outer chloroplast membrane) and Tic- (translocon at the inner chloroplast membrane) complexes. In Arabidopsis thaliana, precursor recognition is mainly mediated by outer membrane receptors belonging to two gene families: Toc34/33 and Toc159/132/120/90. The role in import and precursor selectivity of these receptors has been intensively studied, but the function of Toc90 still remains unclear. Here, we report the ability of Toc90 to support the import of Toc159 client proteins. We show that the overexpression of Toc90 partially complements the albino knockout of Toc159 and restores photoautotrophic growth. Several lines of evidence including proteome profiling demonstrate the import and accumulation of proteins essential for chloroplast biogenesis and functionality.
authors.affiliation: Laboratoire de physiologie végétale, Université de Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland.
authors.forename: Sibylle
authors.initials: S
authors.lastname: Infanger
authors.forename: Sylvain
authors.initials: S
authors.lastname: Bischof
authors.forename: Andreas
authors.initials: A
authors.lastname: Hiltbrunner
authors.forename: Birgit
authors.initials: B
authors.lastname: Agne
authors.forename: Sacha
authors.initials: S
authors.lastname: Baginsky
authors.forename: Felix
authors.initials: F
authors.lastname: Kessler
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D021381:Protein Transport / Q000235:genetics / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D008565:Membrane Proteins; C403444:TOC159 protein, Arabidopsis; C491156:Toc90 protein, Arabidopsis; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins