The Protein Disulfide Isomerase-like RB60 Is Partitioned between Stroma and Thylakoids in Chlamydomonas reinhardtii Chloroplasts

Trebitsh, Tova; E, Meiri; Ostersetzer, Oren; Adam, Zach; Danon, Avihai

doi:10.1074/jbc.m005950200

Cited by 60 publications

(31 citation statements)

References 56 publications

(63 reference statements)

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“…2c, lane 3 and in ref. 7), strengthening our assumption that the dual import of RB60 to the ER and chloroplasts occurs via the two mutually exclusive conserved targeting mechanisms.…”

Section: Resultsmentioning

confidence: 53%

“…The C. reinhardtii RB60 is a PDI that functions as a regulatory protein in the chloroplast, where it is found in both soluble and membrane-associated forms (7). Here, we show that, in addition to its chloroplast function, RB60 is localized to the ER (Fig.…”

Section: Discussionmentioning

confidence: 61%

“…In the chloroplast under steady-state conditions, RB60 is partitioned between a soluble form in the stroma and a form that is tightly bound to the photosynthetic thylakoid membranes. However, the newly imported RB60 is apparently directed first to the thylakoids (7).…”

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confidence: 99%

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Dual targeting of the protein disulfide isomerase RB60 to the chloroplast and the endoplasmic reticulum

Levitan

Trebitsh

Kiss

et al. 2005

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

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RB60 is an atypical protein disulfide isomerase (PDI) that functions as a member of a redox regulatory protein complex controlling translation in the chloroplast of Chlamydomonas reinhardtii, but also contains a C-terminal endoplasmic reticulum (ER) retention signal, -KDEL. Here, we show by fluorescence microscopy that RB60 resides in the chloroplast but also outside of the chloroplast colocalized with BiP, an ER marker protein. RB60 accumulates in microsomes that exhibit a typical ER magnesium-shift, and cotranslationally translocates into ER microsomes. The first 50-aa leader of RB60 is sufficient for both chloroplast and ER targeting. The leader is cleaved upon translocation into the ER, whereas it remains intact after import to the chloroplast. The leader sequence also contains an acidic domain that appears necessary for the protein's association with the thylakoid membranes. Based on these and additional results, we propose that the dual localization of RB60 occurs via the two conserved transport mechanisms, to the chloroplast and to the ER, that the chloroplast RB60 most likely carries an additional function in the ER, and that its mode of transport, including the differential cleavage of its N terminus, plays an important role in its suborganellar localization and organellarspecific function.dual subcellular localization ͉ redox-responsive regulator ͉ membrane association ͉ GFP

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“…2c, lane 3 and in ref. 7), strengthening our assumption that the dual import of RB60 to the ER and chloroplasts occurs via the two mutually exclusive conserved targeting mechanisms.…”

Section: Resultsmentioning

confidence: 53%

Section: Discussionmentioning

confidence: 61%

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Dual targeting of the protein disulfide isomerase RB60 to the chloroplast and the endoplasmic reticulum

Levitan

Trebitsh

Kiss

et al. 2005

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

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“…Whereas some RNA binding proteins are membrane embedded or show reversible association with the membrane (Zerges and Rochaix, 1998;Trebitsh et al, 2001;Ossenbü hl et al, 2002;Zerges et al, 2002;Schult et al, 2007), MCA1 and TCA1, as most trans-acting factors (e.g., CRP1 [Fisk et al, 1999], NAC2 [Boudreau, 2000], MBB1 [Vaistij et al, 2000b], and TAB2 [Dauvillé e et al, 2003]), are found in the chloroplast stroma. The functional significance of these contrasting distributions is still unclear but could reflect differences in the mode of action of nucleus-encoded factors: some may remain bound to polysomes, while others bind transiently to their target mRNA but dissociate once translation is initiated.…”

Section: Discussionmentioning

confidence: 99%

The Nucleus-Encodedtrans-Acting Factor MCA1 Plays a Critical Role in the Regulation of CytochromefSynthesis inChlamydomonasChloroplasts

et al. 2011

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Organelle gene expression is characterized by nucleus-encoded trans-acting factors that control posttranscriptional steps in a gene-specific manner. As a typical example, in Chlamydomonas reinhardtii, expression of the chloroplast petA gene encoding cytochrome f, a major subunit of the cytochrome b 6 f complex, depends on MCA1 and TCA1, required for the accumulation and translation of the petA mRNA. Here, we show that these two proteins associate in high molecular mass complexes that also contain the petA mRNA. We demonstrate that MCA1 is degraded upon interaction with unassembled cytochrome f that transiently accumulates during the biogenesis of the cytochrome b 6 f complex. Strikingly, this interaction relies on the very same residues that form the repressor motif involved in the Control by Epistasy of cytochrome f Synthesis (CES), a negative feedback mechanism that downregulates cytochrome f synthesis when its assembly within the cytochrome b 6 f complex is compromised. Based on these new findings, we present a revised picture for the CES regulation of petA mRNA translation that involves proteolysis of the translation enhancer MCA1, triggered by its interaction with unassembled cytochrome f.

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“…The relationships in this isomerase family are shown in Figure 4 in the form of a rooted tree with three main clades. None of these isomerases were identical to other known chloroplast isomerases, such FKBP13 (Luan et al, 1994a), ROC4 in the stroma (Lippuner et al, 1994), cyclophilin pCyP B (Luan et al, 1994b), RB60, a protein disulfide isomerase involved in translation regulation (Kim and Mayfield, 1997;Trebitsh et al, 2000), or any of the other known cytosolic isomerases (ROC1, -2, -3, -5, or -6) (Chou and Gasser, 1997). On the basis of the presence of a closely spaced cysteine pair, it is possible that spots 110 and 211 and At5g45680 (indicated in Figure 4) have a specific function as an oxidative folding catalyst.…”

Section: Expression Of Multiple Isomerases and Proteasesmentioning

confidence: 99%

Central Functions of the Lumenal and Peripheral Thylakoid Proteome of Arabidopsis Determined by Experimentation and Genome-Wide Prediction

Peltier

Emanuelsson

Kalume³

et al. 2002

Plant Cell

426

382

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Experimental proteome analysis was combined with a genome-wide prediction screen to characterize the protein content of the thylakoid lumen of Arabidopsis chloroplasts. Soluble thylakoid proteins were separated by two-dimensional electrophoresis and identified by mass spectrometry. The identities of 81 proteins were established, and N termini were sequenced to validate localization prediction. Gene annotation of the identified proteins was corrected by experimental data, and an interesting case of alternative splicing was discovered. Expression of a surprising number of paralogs was detected. Expression of five isomerases of different classes suggests strong (un)folding activity in the thylakoid lumen. These isomerases possibly are connected to a network of peripheral and lumenal proteins involved in antioxidative response, including peroxiredoxins, m-type thioredoxins, and a lumenal ascorbate peroxidase. Characteristics of the experimentally identified lumenal proteins and their orthologs were used for a genome-wide prediction of the lumenal proteome. Lumenal proteins with a typical twin-arginine translocation motif were predicted with good accuracy and sensitivity and included additional isomerases and proteases. Thus, prime functions of the lumenal proteome include assistance in the folding and proteolysis of thylakoid proteins as well as protection against oxidative stress. Many of the predicted lumenal proteins must be present at concentrations at least 10,000-fold lower than proteins of the photosynthetic apparatus.

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The Protein Disulfide Isomerase-like RB60 Is Partitioned between Stroma and Thylakoids in Chlamydomonas reinhardtii Chloroplasts

Cited by 60 publications

References 56 publications

Dual targeting of the protein disulfide isomerase RB60 to the chloroplast and the endoplasmic reticulum

Dual targeting of the protein disulfide isomerase RB60 to the chloroplast and the endoplasmic reticulum

The Nucleus-Encodedtrans-Acting Factor MCA1 Plays a Critical Role in the Regulation of CytochromefSynthesis inChlamydomonasChloroplasts

Central Functions of the Lumenal and Peripheral Thylakoid Proteome of Arabidopsis Determined by Experimentation and Genome-Wide Prediction

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