Protein Translocation within Chloroplast Is Similar in Euglena and Higher Plants

Inagaki, Jiro; Fujita, Yuichi; Hase, Toshiharu; Yamamoto, Yasusi

doi:10.1006/bbrc.2000.3702

Cited by 17 publications

(18 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast to one report (Shashidhara et al, 1992) but confirming another (Inagaki et al, 2000), a pSSU lacking the pre-sequence signal peptide domain was imported into pea chloroplasts in an ATP dependent reaction. The pre-sequence membrane anchor that is not translocated across the ER membrane is translocated across the pea chloroplast envelope.…”

Section: Discussioncontrasting

confidence: 53%

“…Euglena pSSU is post-translationally imported into pea chloroplasts In vitro import into plant chloroplasts has demonstrated that pre-sequences of proteins imported into complex plastids contain a plant-like transit peptide (DeRocher et al, 2000;Inagaki et al, 2000;Lang et al, 1998;Nassoury et al, 2003;Wastl and Maier, 2000) but conflicting reports have appeared regarding the ability of the Euglena pre-sequence to target proteins to plant chloroplasts (Inagaki et al, 2000;Shashidhara et al, 1992). Import of Euglena pSSU, a stromal enzyme, into higher plant chloroplasts was used to determine if the Euglena pre-sequence is recognized by the higher plant import apparatus and to define the recognized domain.…”

Section: Euglena Golgi To Chloroplast Transport Is Reversibly Blockedmentioning

confidence: 99%

“…Conflicting reports have appeared regarding the functionality of the Euglena pre-sequence with higher plant chloroplasts (Inagaki et al, 2000;Shashidhara et al, 1992) and it is unclear whether Euglena pre-sequences contain a functional transit peptide. In vivo studies have shown that the transit peptide is the sorting signal directing precursors from the secretory pathway to the diatom plastid (Apt et al, 2002) and the apicoplast (DeRocher et al, 2000;Waller et al, 2000).…”

mentioning

confidence: 99%

See 2 more Smart Citations

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

Sláviková

Vacula

Fang

et al. 2005

Journal of Cell Science

View full text Add to dashboard Cite

Euglena complex chloroplasts evolved through secondary endosymbiosis between a phagotrophic trypanosome host and eukaryotic algal endosymbiont. Cytoplasmically synthesized chloroplast proteins are transported in vesicles as integral membrane proteins from the ER to the Golgi apparatus to the Euglena chloroplast. Euglena chloroplast preprotein pre-sequences contain a functional N-terminal ER-targeting signal peptide and a domain having characteristics of a higher plant chloroplast targeting transit peptide, which contains a hydrophobic stop-transfer membrane anchor sequence that anchors the precursor in the vesicle membrane. Pulse-chase subcellular fractionation studies showed that 35S-labeled precursor to the light harvesting chlorophyll a/b binding protein accumulated in the Golgi apparatus of Euglena incubated at 15°C and transport to the chloroplast resumed after transfer to 26°C. Transport of the 35S-labeled precursor to the chlorophyll a/b binding protein from Euglena Golgi membranes to Euglena chloroplasts and import into chloroplasts was reconstituted using Golgi membranes isolated from 15°C cells returned to 26°C. Transport was dependent upon extra- and intrachloroplast ATP and GTP hydrolysis. Golgi to chloroplast transport was not inhibited by N-ethylmaleimide indicating that fusion of Golgi vesicles to the chloroplast envelope does not require N-ethylmaleimide-sensitive factor (NSF). This suggests that N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are not utilized in the targeting fusion reaction. The Euglena precursor to the chloroplast-localized small subunit of ribulose-1,5-bisphosphate carboxylase was not imported into isolated pea chloroplasts. A precursor with the N-terminal signal peptide deleted was imported, indicating that the Euglena pre-sequence has a transit peptide that functions in pea chloroplasts. A precursor to the small subunit of ribulose-1,5-bisphosphate carboxylase with the hydrophobic membrane anchor and the pre-sequence region C-terminal to the hydrophobic membrane anchor deleted was imported localizing the functional transit peptide to the Euglena pre-sequence region between the signal peptidase cleavage site and the hydrophobic membrane anchor. The Euglena precursor to the small subunit of ribulose-1,5-bisphosphate carboxylase and the deletion constructs were not post-translationally imported into isolated Euglena chloroplasts indicating that vesicular transport is the obligate import mechanism. Taken together, these studies suggest that protein import into complex Euglena chloroplasts evolved by developing a novel vesicle fusion targeting system to link the host secretory system to the transit peptide-dependent chloroplast protein import system of the endosymbiont.

show abstract

Section: Discussioncontrasting

confidence: 53%

Section: Euglena Golgi To Chloroplast Transport Is Reversibly Blockedmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

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

Sláviková

Vacula

Fang

et al. 2005

Journal of Cell Science

View full text Add to dashboard Cite

show abstract

“…Although sequence conservation per se is lacking, there is a general maintenance of certain chemical properties, including enrichment for the hydroxylated amino acids serine and threonine and a deficiency in acidic residues (76). In Euglena class I proteins, the intervening region between the two TMHs likely functions as a plastid TP (29). For class II proteins, we predicted that the region immediately following the signal sequence must have a role in targeting to the plastid.…”

Section: Cluster 3881 [Atp/adp Transporter])mentioning

confidence: 99%

“…From studies of several complete, publicly available Euglena gracilis plastid protein sequences (13,25,27,28,38,44,52,56,61,64,66,73), it was predicted that the plastid proteins have an N-terminal signal sequence, an inference that was confirmed by both in vitro (38) and in vivo (70,71) experimental approaches. Following the signal sequence is the predicted transit peptide, which is sufficient for translocation across plant chloroplast membranes (29), and a hydrophobic region that acts as a "stoptransfer" sequence to prevent complete transport into the ER, such that the mature protein remains in the cytoplasm (69). The protein is then targeted to the plastid, likely via a vesicular transport system (67).…”

mentioning

confidence: 99%

Analysis of Euglena gracilis Plastid-Targeted Proteins Reveals Different Classes of Transit Sequences

2006

View full text Add to dashboard Cite

The plastid of Euglena gracilis was acquired secondarily through an endosymbiotic event with a eukaryotic green alga, and as a result, it is surrounded by a third membrane. This membrane complexity raises the question of how the plastid proteins are targeted to and imported into the organelle. To further explore plastid protein targeting in Euglena, we screened a total of 9,461 expressed sequence tag (EST) clusters (derived from 19,013 individual ESTs) for full-length proteins that are plastid localized to characterize their targeting sequences and to infer potential modes of translocation. Of the 117 proteins identified as being potentially plastid localized whose N-terminal targeting sequences could be inferred, 83 were unique and could be classified into two major groups. Class I proteins have tripartite targeting sequences, comprising (in order) an N-terminal signal sequence, a plastid transit peptide domain, and a predicted stop-transfer sequence. Within this class of proteins are the lumen-targeted proteins (class IB), which have an additional hydrophobic domain similar to a signal sequence and required for further targeting across the thylakoid membrane. Class II proteins lack the putative stop-transfer sequence and possess only a signal sequence at the N terminus, followed by what, in amino acid composition, resembles a plastid transit peptide. Unexpectedly, a few unrelated plastid-targeted proteins exhibit highly similar transit sequences, implying either a recent swapping of these domains or a conserved function. This work represents the most comprehensive description to date of transit peptides in Euglena and hints at the complex routes of plastid targeting that must exist in this organism.A fundamental problem in cell biology is the precise and efficient targeting of proteins synthesized by cytoplasmic ribosomes to their appropriate intracellular locations. Proteins destined for the endomembrane system, mitochondria, or the chloroplast usually have specific N-terminal targeting domains that are required for proper subcellular localization. These leader sequences are often removed by specific proteases at the protein's destination prior to it assuming its active conformation. For chloroplast-targeted proteins in plants and algae, an N-terminal transit peptide (TP) is both necessary and sufficient for correct plastid targeting (11). Transit peptides are not conserved in sequence but exhibit characteristic biochemical properties, such as an elevated content of the hydroxylated amino acids serine and threonine as well as a deficiency of acidic (aspartate and glutamate) amino acids (76). Within a typical chloroplast, there are six distinct locations to which the constituent proteins must be sorted, and some proteins have to cross up to three membranes (33). This complexity requires additional targeting information within the transit peptide, such as the signal sequence-like domain found in proteins targeted to the thylakoid membrane, or information contained within the mature portion of the protein itself...

show abstract

Protein Import Into Chloroplasts: Who, When, and How?

Vothknecht

Soll

2007

Advances in Photosynthesis and Respiration

View full text Add to dashboard Cite

Protein Translocation within Chloroplast Is Similar in Euglena and Higher Plants

Cited by 17 publications

References 47 publications

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

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

Analysis of Euglena gracilis Plastid-Targeted Proteins Reveals Different Classes of Transit Sequences

Protein Import Into Chloroplasts: Who, When, and How?

Contact Info

Product

Resources

About