Protein translocation into and across the chloroplastic envelope membranes

Soll, Jürgen; Tien, R.

doi:10.1007/978-94-011-5298-3_10

Cited by 46 publications

(39 citation statements)

References 128 publications

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“…Protease-resistant fragments are called deg and classified into deg1, deg2, deg3, or deg4 based on different molecular sizes, from the largest (deg1) to the smallest (deg4). deg1 and deg2 were shown to cofractionate with the outer membrane, whereas deg3 and deg4, which would correspond to SSU-DPs in this study, were shown to cofractionate with the inner membrane (Waegemann and Soll, 1993;Soll and Tien, 1998), supporting our observations. Akita et al (1997) have shown that a translocation intermediate complex of ;600 kD could be isolated using chemical crosslinkers.…”

Section: Mbs As In (A)supporting

confidence: 89%

A 1-Megadalton Translocation Complex Containing Tic20 and Tic21 Mediates Chloroplast Protein Import at the Inner Envelope Membrane

et al. 2009

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Chloroplast protein import is mediated by two hetero-oligomeric protein complexes, the Tic and Toc translocons, which are located in the inner and outer envelope membranes. At the inner membrane, many Tic components have been identified and characterized, but it remains unclear how these Tic proteins are organized to form a protein-conducting channel or whether a stable Tic core complex that binds translocating preproteins exists. Here, we report the identification of a 1-megadalton (MD) translocation complex as an intermediate during protein translocation across the inner membrane in Arabidopsis thaliana and pea (Pisum sativum). This complex can be detected by blue native PAGE using the mild detergent digitonin without any chemical cross-linkers. The preprotein arrested in the 1-MD complex can be chased into its fully translocated form after a subsequent incubation. While Tic20 and Tic21 appear to be involved in the 1-MD complex, Tic110, a wellcharacterized Tic component, exists as a distinct entity from the complex. Several lines of evidence suggest that the 1-MD complex functions in between the Toc and Tic110-containing complexes, most likely as a protein-conducting channel at the inner envelope.

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Section: Mbs As In (A)supporting

confidence: 89%

A 1-Megadalton Translocation Complex Containing Tic20 and Tic21 Mediates Chloroplast Protein Import at the Inner Envelope Membrane

et al. 2009

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“…(e) Targeting to the apicoplast In mitochondria and chloroplasts, considerable effort has been invested in identifying the mechanisms whereby nuclear-encoded proteins are imported across the one, two, or three membranes separating distinct organellar compartments from the cytosol (Pilon et al 1995;Cline & Henry 1996;Haucke & Schatz 1997;Martin & Hermann 1998;Soll & Tien 1998). Import signals are not well conserved, typically consisting of weakly basic amphipathic alpha helices; these N-terminal domains are cleaved upon import into the organelle.…”

Section: (D) Apicoplast Proteinsmentioning

confidence: 99%

“…Unfortunately, as noted above, there is no reliable method for recognizing nuclear-encoded apicoplast proteins (as is the case for proteins destined for mitochondria or chloroplasts): apicoplast-targeting signals are highly degenerate. Probable homologues of chloroplast proteins, known to be encoded in the nuclear genome of plants or algae (Cline & Henry 1996;Haucke & Schatz 1997;Soll & Tien 1998;Martin & Hermann 1998; include hundreds of candidate genes, including, for example, cytoplasmic and mitochondrial ribosomal proteins, in addition to their counterparts destined for the apicoplast. Similarly, predicted signal sequences may be found on proteins destined for the rhoptries, micronemes, dense granules, parasite plasma membrane, parasitophorous vacuole, or host cell ... in addition to nuclearencoded plastid proteins.…”

Section: (F ) But What Does the Apicoplast Do?mentioning

confidence: 99%

Mining thePlasmodiumgenome database to define organellar function: what does the apicoplast do?

Roos

Crawford

Donald

et al. 2002

Phil. Trans. R. Soc. Lond. B

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Apicomplexan species constitute a diverse group of parasitic protozoa, which are responsible for a wide range of diseases in many organisms. Despite differences in the diseases they cause, these parasites share an underlying biology, from the genetic controls used to differentiate through the complex parasite life cycle, to the basic biochemical pathways employed for intracellular survival, to the distinctive cell biology necessary for host cell attachment and invasion. Different parasites lend themselves to the study of different aspects of parasite biology: Eimeria for biochemical studies, Toxoplasma for molecular genetic and cell biological investigation, etc. The Plasmodium falciparum Genome Project contributes the first large-scale genomic sequence for an apicomplexan parasite. The Plasmodium Genome Database (http://PlasmoDB. org) has been designed to permit individual investigators to ask their own questions, even prior to formal release of the reference P. falciparum genome sequence. As a case in point, PlasmoDB has been exploited to identify metabolic pathways associated with the apicomplexan plastid, or 'apicoplast'-an essential organelle derived by secondary endosymbiosis of an alga, and retention of the algal plastid.

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“…The development and maintenance of specific plastid types in different tissues (e.g., chloroplasts in green tissues) relies on the import and assembly of several thousand different nucleus-encoded proteins (Soll and Tien, 1998;Chen and Schnell, 1999;Keegstra and Cline, 1999;Keegstra and Froehlich, 1999). This requires a remarkable flexibility in the import apparatus because the relative amounts and compositions of imported proteins vary considerably depending on the type and developmental stage of the particular plastid.…”

Section: Introductionmentioning

confidence: 99%

“…Although there is no consensus for the length or sequence of transit peptides from different preproteins (von Heijne et al, 1989;von Heijne and Nishikawa, 1991;Bruce, 2001), original studies of the mechanism of protein import led to the proposal that transit peptides are functionally interchangeable (Mishkind et al, 1985;Van den Broeck et al, 1985;de Boer et al, 1991) and are recognized by a common, general protein import machinery (Soll and Tien, 1998). In chloroplasts, transit peptides are recognized by receptor components of the preprotein translocon at the outer envelope membrane of chloroplasts (Toc complex) (Hirsch et al, 1994;Perry and Keegstra, 1994;Schnell et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

Members of the Toc159 Import Receptor Family Represent Distinct Pathways for Protein Targeting to Plastids

Ivanova

Smith

Chen

et al. 2004

MBoC

182

329

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Plastids represent a diverse group of organelles that perform essential metabolic and signaling functions within all plant cells. The differentiation of specific plastid types relies on the import of selective sets of proteins from among the ϳ2500 nucleus-encoded plastid proteins. The Toc159 family of GTPases mediates the initial targeting of proteins to plastids. In Arabidopsis thaliana, the Toc159 family consists of four genes: atTOC159, atTOC132, atTOC120, and atTOC90. In vivo analysis of atToc159 function indicates that it is required specifically for the import of proteins necessary for chloroplast biogenesis. In this report, we demonstrate that atToc120 and atToc132 represent a structurally and functionally unique subclass of protein import receptors. Unlike atToc159, mutants lacking both atToc120 and atToc132 are inviable. Furthermore, atToc120 and atToc132 exhibit preprotein binding properties that are distinct from atToc159. These data indicate that the different members of the Toc159 family represent distinct pathways for protein targeting to plastids and are consistent with the hypothesis that separate pathways have evolved to ensure balanced import of essential proteins during plastid development.

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Protein translocation into and across the chloroplastic envelope membranes

Cited by 46 publications

References 128 publications

A 1-Megadalton Translocation Complex Containing Tic20 and Tic21 Mediates Chloroplast Protein Import at the Inner Envelope Membrane

A 1-Megadalton Translocation Complex Containing Tic20 and Tic21 Mediates Chloroplast Protein Import at the Inner Envelope Membrane

Mining thePlasmodiumgenome database to define organellar function: what does the apicoplast do?

Members of the Toc159 Import Receptor Family Represent Distinct Pathways for Protein Targeting to Plastids

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