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Essential role of the G-domain in targeting of the protein import receptor atToc159 to the chloroplast outer membrane
Auteur(s)
Bauer, Jörg
Hiltbrunner, Andreas
Vidi, Pierre-Alexandre
Alvarez-Huerta, Mayte
Smith, Matthew
Schnell, Danny
Date de parution
2002
In
Journal of Cell Biology
Vol.
5
No
159
De la page
845
A la page
854
Mots-clés
Résumé
Two 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.
Identifiants
Type de publication
journal article
