Identification and characterization of a new conserved motif within the presequence of proteins targeted into complex diatom plastids

Kilian, Oliver; Kroth, Peter G.

doi:10.1111/j.1365-313x.2004.02294.x

Cited by 186 publications

(241 citation statements)

References 34 publications

(52 reference statements)

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“…In Vivo Localization in the Diatom P. tricornutum-Analyzing the targeting properties of the first two of the three N-terminal topogenic signals of PE␣ revealed the same results as with similar constructs from recent reports (10,19,20). The signal peptide alone targets GFP to the ER, which is distributed throughout the diatom cell (Fig.…”

Section: Cloning Of Nuclear-encoded Plastid Proteins Of G Theta-oursupporting

confidence: 65%

Translocation of a Phycoerythrin α Subunit across Five Biological Membranes

Gould

Fan

Hempel

et al. 2007

Journal of Biological Chemistry

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Cryptophytes, unicellular algae, evolved by secondary endosymbiosis and contain plastids surrounded by four membranes. In contrast to cyanobacteria and red algae, their phycobiliproteins do not assemble into phycobilisomes and are located within the thylakoid lumen instead of the stroma. We identified two gene families encoding phycoerythrin ␣ and light-harvesting complex proteins from an expressed sequence tag library of the cryptophyte Guillardia theta. The proteins bear a bipartite topogenic signal responsible for the transport of nuclear encoded proteins via the ER into the plastid. Analysis of the phycoerythrin ␣ sequences revealed that more than half of them carry an additional, third topogenic signal comprising a twin arginine motif, which is indicative of Tat (twin arginine transport)-specific targeting signals. We performed import studies with several derivatives of one member using a diatom transformation system, as well as intact chloroplasts and thylakoid vesicles isolated from pea. We demonstrated the different targeting properties of each individual part of the tripartite leader and show that phycoerythrin ␣ is transported across the thylakoid membrane into the thylakoid lumen and protease-protected. Furthermore, we showed that thylakoid transport of phycoerythrin ␣ takes place by the Tat pathway even if the 36 amino acid long bipartite topogenic signal precedes the actual twin arginine signal. This is the first experimental evidence of a protein being targeted across five biological membranes.

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Section: Cloning Of Nuclear-encoded Plastid Proteins Of G Theta-oursupporting

confidence: 65%

Translocation of a Phycoerythrin α Subunit across Five Biological Membranes

Gould

Fan

Hempel

et al. 2007

Journal of Biological Chemistry

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“…In that case, one has to postulate that glycosylation residues in combination with the transit peptide serve as a targeting signal. Model III: A third possibility would be that there exists an alternative vesiclemediated pathway between the second and third plastid membranes, which was postulated in a different context (not for glycoproteins) previously (11). Also in that model the transit peptide together with the N-glycans should serve as a recognition signal to discriminate these proteins from other secretory glycoproteins.…”

Section: Discussionmentioning

confidence: 99%

“…Transport across that first membrane is mediated cotranslationally via the Sec61 translocation complex and a signal peptide at the N terminus is essential for that translocation step into the chloroplast ER (cER) (6)(7)(8). To cross the remaining plastid membranes i.e., the second plastid membrane, which presumably originated from the plasma membrane of the red algal endosymbiont, and membranes three and four, a second targeting signal is necessary, which is a transit peptide-like sequence (9)(10)(11). Signal peptide and transit peptide together are called bipartite targeting signal (BTS) and represent the classical targeting signature for preproteins destined to complex plastids.…”

mentioning

confidence: 99%

Evidence for glycoprotein transport into complex plastids

Peschke¹,

Moog

Klingl

et al. 2013

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

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Diatoms are microalgae that possess so-called "complex plastids," which evolved by secondary endosymbiosis and are surrounded by four membranes. Thus, in contrast to primary plastids, which are surrounded by only two membranes, nucleus-encoded proteins of complex plastids face additional barriers, i.e., during evolution, mechanisms had to evolve to transport preproteins across all four membranes. This study reveals that there exist glycoproteins not only in primary but also in complex plastids, making transport issues even more complicated, as most translocation machineries are not believed to be able to transport bulky proteins. We show that plastidal reporter proteins with artificial N-glycosylation sites are indeed glycosylated during transport into the complex plastid of the diatom Phaeodactylum tricornutum. Additionally, we identified five endogenous glycoproteins, which are transported into different compartments of the complex plastid. These proteins get N-glycosylated during transport across the outermost plastid membrane and thereafter are transported across the second, third, and fourth plastid membranes in the case of stromal proteins. The results of this study provide insights into the evolutionary pressure on translocation mechanisms and pose unique questions on the operating mode of well-known transport machineries like the translocons of the outer/inner chloroplast membranes (Toc/Tic).

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“…In cryptophytes, heterokonts, and perhaps apicomplexans, an N-terminal aromatic amino acid of TPL is involved in transporting preproteins across the 2 innermost plastid membranes (11,(16)(17)(18)(19). These groups have red algal-derived secondary plastids, and it has been known that the TPs of red algae also possess a conserved aromatic amino acid at the N termini (11).…”

Section: Ppc-to-stroma Transport Signal In the Tplmentioning

confidence: 99%

“…The plastids of heterokonts and cryptophytes are surrounded by 4 membranes; the outermost membrane is continuous with the ER. Their TPLs possess a conserved aromatic amino acid (such as phenylalanine) at the N terminus, and it has been demonstrated that this aromatic amino acid is necessary in allowing preproteins to pass through the 2 innermost plastid membranes (16)(17)(18)(19). Apicomplexans have nonphotosynthetic plastids (apicoplasts) surrounded by 4 smooth membranes.…”

mentioning

confidence: 99%

Protein targeting into secondary plastids of chlorarachniophytes

Hirakawa

Nagamune²,

Ishida³

2009

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

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Most plastid proteins are encoded by the nuclear genome, and consequently, need to be transported into plastids across multiple envelope membranes. In diverse organisms possessing secondary plastids, nuclear-encoded plastid precursor proteins (preproteins) commonly have an N-terminal extension that consists of an endoplasmic reticulum (ER)-targeting signal peptide and a transit peptide-like sequence (TPL). This bipartite targeting peptide is believed to be necessary for targeting the preproteins into the secondary plastids. Here, we newly demonstrate the function of the bipartite targeting peptides of an algal group, chlorarachniophytes, and characterize the functional domains of the TPL in the precursor of a plastid protein, ATP synthase delta subunit (AtpD), using a GFP as a reporter molecule. We show that the C-terminal portion of the TPL is important for targeting the AtpD preprotein from the ER into the chlorarachniophyte plastids, and several positively charged amino acids in the TPL are also necessary for transporting the preprotein across the 2 innermost plastid membranes. Compared with other groups with secondary plastids, the TPL functional domains of the chlorarachniophytes are unique, which might be caused by independent acquisition of their plastids.ATP synthase delta subunit ͉ secondary endosymbiosis ͉ transit peptides ͉ bipartite targeting peptide ͉ periplastidal compartment

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Identification and characterization of a new conserved motif within the presequence of proteins targeted into complex diatom plastids

Cited by 186 publications

References 34 publications

Translocation of a Phycoerythrin α Subunit across Five Biological Membranes

Translocation of a Phycoerythrin α Subunit across Five Biological Membranes

Evidence for glycoprotein transport into complex plastids

Protein targeting into secondary plastids of chlorarachniophytes

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