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First published online April 5, 2005

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Novel import route for plastid

The complex chloroplast of Euglena evolved through secondary endosymbiosis between a trypanosome host and an algal endosymbiont. In Euglena, nuclear-encoded chloroplast proteins are transported to the chloroplast in vesicles via the ER and Golgi as integral membrane proteins. Steven Schwartzbach and co-workers have now reconstituted this transport system in vitro (see p. 1651). The authors preload Golgi membranes with a ³⁵S-labeled precursor of the light-harvesting chlorophyll a/b binding protein, isolate the membranes, mix them with isolated chloroplasts and track precursor import by following its proteolytic processing in the chloroplast. They show that Golgi-to-chloroplast transport requires light, ATP and GTP but not N-ethylmaleimide-sensitive factor, which indicates that the SNARE proteins common in other vesicle-trafficking pathways are not used. They also uncover information about the signals in Euglena chloroplast protein presequences that are required for plastid import and conclude that during its evolution Euglena developed a novel vesicle-targeting system to link the host secretory system to the transit-peptide-dependent chloroplast import system of the endosymbiont.

Related articles in JCS:

Homologous and heterologous reconstitution of Golgi to chloroplast transport and protein import into the complex chloroplasts of Euglena

Silvia Sláviková, Rostislav Vacula, Zhiwei Fang, Tomoko Ehara, Tetsuaki Osafune, and Steven D. Schwartzbach
JCS 2005 118: 1651-1661. [Abstract] [Full Text]  

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JCS Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content