Topology of Euglena Chloroplast Protein Precursors within Endoplasmic Reticulum to Golgi to Chloroplast Transport Vesicles

Sulli, Chidananda; Fang, Zhiwei; Muchhal, Umesh S.; Schwartzbach, Steven D.

doi:10.1074/jbc.274.1.457

Cited by 99 publications

(139 citation statements)

References 46 publications

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“…A distinct bipartite signal, identified at the N terminus of all apicoplast-targeted proteins to date, is sufficient to transport reporter proteins to the apicoplast (1,5,6). This transport is similar to the plastid-targeting mechanism found for nuclear-encoded proteins imported into three-or fourmembrane plastids in other species (7)(8)(9). In plants, protein import into plastids is mediated by a 25-to 125-aa N-terminal transit peptide with no clear sequence consensus among the many proteins imported.…”

mentioning

confidence: 72%

Subcellular localization of acetyl-CoA carboxylase in the apicomplexan parasite Toxoplasma gondii

Jeleńska

Crawford

Harb

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

107

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Apicomplexan parasites such as Toxoplasma gondii contain a primitive plastid, the apicoplast, whose genome consists of a 35-kb circular DNA related to the plastid DNA of plants. Plants synthesize fatty acids in their plastids. The first committed step in fatty acid synthesis is catalyzed by acetyl-CoA carboxylase (ACC). This enzyme is encoded in the nucleus, synthesized in the cytosol, and transported into the plastid. In the present work, two genes encoding ACC from T. gondii were cloned and the gene structure was determined. Both ORFs encode multidomain proteins, each with an N-terminal extension, compared with the cytosolic ACCs from plants. The N-terminal extension of one isozyme, ACC1, was shown to target green fluorescent protein to the apicoplast of T. gondii . In addition, the apicoplast contains a biotinylated protein, consistent with the assertion that ACC1 is localized there. The second ACC in T. gondii appears to be cytosolic. T. gondii mitochondria also contain a biotinylated protein, probably pyruvate carboxylase. These results confirm the essential nature of the apicoplast and explain the inhibition of parasite growth in cultured cells by herbicides targeting ACC.

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mentioning

confidence: 72%

Subcellular localization of acetyl-CoA carboxylase in the apicomplexan parasite Toxoplasma gondii

Jeleńska

Crawford

Harb

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

107

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“…from algae with primary plastids through secondary endosymbioses (19)] were shown to passage through the Golgi (20,21). Plastid proteins synthesized in the cytoplasm of these algal cells have Nterminal, bipartite presequences composed of an ER-targeting signal [signal peptide (SP)] and a TP-like sequence.…”

Section: Discussionmentioning

confidence: 99%

Trafficking of protein into the recently established photosynthetic organelles of Paulinella chromatophora

Nowack

Grossman²

2012

Proc. Natl. Acad. Sci. U.S.A.

146

126

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Endosymbiotic acquisition of bacteria by a protist, with subsequent evolution of the bacteria into mitochondria and plastids, had a transformative impact on eukaryotic biology. Reconstructing events that created a stable association between endosymbiont and host during the process of organellogenesis—including establishment of regulated protein import into nascent organelles—is difficult because they date back more than 1 billion years. The amoeba Paulinella chromatophora contains nascent photosynthetic organelles of more recent evolutionary origin (∼60 Mya) termed chromatophores (CRs). After the initial endosymbiotic event, the CR genome was reduced to approximately 30% of its presumed original size and more than 30 expressed genes were transferred from the CR to the amoebal nuclear genome. Three transferred genes— psaE , psaK1 , and psaK2 —encode subunits of photosystem I. Here we report biochemical evidence that PsaE, PsaK1, and PsaK2 are synthesized in the amoeba cytoplasm and traffic into CRs, where they assemble with CR-encoded subunits into photosystem I complexes. Additionally, our data suggest that proteins routed to CRs pass through the Golgi apparatus. Whereas genome reduction and transfer of genes from bacterial to host genome have been reported to occur in other obligate bacterial endosymbioses, this report outlines the import of proteins encoded by such transferred genes into the compartment derived from the bacterial endosymbiont. Our study showcases P . chromatophora as an exceptional model in which to study early events in organellogenesis, and suggests that protein import into bacterial endosymbionts might be a phenomenon much more widespread than currently assumed.

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“…In one mechanism, such as that used by haptophytes and diatoms, ribosomes are attached directly to the outer plastid membrane. After passage of the first (outermost) membrane, termed the chloroplast ER (Gibbs, 1981), proteins either cross the second membrane through large pores, or traverse the subsequent intermembrane space inside transport vesicles (van Dooren et al, 2001). In contrast to this mechanism, targeting to the four membrane-bound plastids of the apicomplexans does not involve ribosomes bound to the outer membrane, and indeed, many aspects of the mechanism are still unknown (van Dooren et al, 2001).…”

mentioning

confidence: 99%

“…crysophytes, apicomplexans and diatoms, all of which contain an N-terminal hydrophobic signal peptide (to target proteins to the ER) followed by a transit sequence which can direct proteins synthesized in vitro to purified plant plastids (van Dooren et al, 2001).…”

mentioning

confidence: 99%

Plastid ultrastructure defines the protein import pathway in dinoflagellates

Nassoury

Cappadocia

Morse

2003

Journal of Cell Science

103

143

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Eukaryotic cells contain a variety of different compartments that are distinguished by their own particular function and characteristic set of proteins. Protein targeting mechanisms to organelles have an additional layer of complexity in algae, where plastids may be surrounded by three or four membranes instead of two as in higher plants. The mechanism of protein import into dinoflagellates plastids, however, has not been previously described despite the importance of plastid targeting in a group of algae responsible for roughly half the ocean's net primary production. Here, we show how nuclear-encoded proteins enter the triple membrane-bound plastids of the dinoflagellate Gonyaulax. These proteins all contain an N-terminal leader sequence with two distinct hydrophobic regions flanking a region rich in hydroxylated amino acids (S/T). We demonstrate that plastid proteins transit through the Golgi in vivo, that the first hydrophobic region in the leader acts as a typical signal peptide in vitro, and that the S/T-rich region acts as a typical plastid transit sequence in transgenic plants. We also show that the second hydrophobic region acts as a stop transfer sequence so that plastid proteins in Golgi-derived vesicles are integral membrane proteins with a predominant cytoplasmic component. The dinoflagellate mechanism is thus different from that used by the phylogenetically related apicomplexans, and instead, is similar to that of the phylogenetically distant Euglena,whose plastids are also bound by three membranes. We conclude that the protein import mechanism is dictated by plastid ultrastructure rather than by the evolutionary history of the cell.

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Topology of Euglena Chloroplast Protein Precursors within Endoplasmic Reticulum to Golgi to Chloroplast Transport Vesicles

Cited by 99 publications

References 46 publications

Subcellular localization of acetyl-CoA carboxylase in the apicomplexan parasite Toxoplasma gondii

Subcellular localization of acetyl-CoA carboxylase in the apicomplexan parasite Toxoplasma gondii

Trafficking of protein into the recently established photosynthetic organelles of Paulinella chromatophora

Plastid ultrastructure defines the protein import pathway in dinoflagellates

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