Isolation and characterization of an amino acid-selective channel protein present in the chloroplastic outer envelope membrane

Pohlmeyer, Kai; Soll, Jürgen; Steinkamp, Thomas; Hinnah, Silke C.; Wagner, Richard

doi:10.1073/pnas.94.17.9504

Cited by 120 publications

(160 citation statements)

References 52 publications

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“…Aligning this sequence with protein sequences found in the databases revealed that it matched a region of the previously identified outer plastid envelope membrane protein Oep16 of pea (39) and barley (40) (Fig. 5A).…”

Section: Resultsmentioning

confidence: 99%

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The outer plastid envelope protein Oep16: Role as precursor translocase in import of protochlorophyllide oxidoreductase A

Reinbothe

Quigley

Springer

et al. 2004

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

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A 16-kDa plastid envelope protein was identified by chemical crosslinking that interacts with the precursor of NADPH:protochlorophyllide oxdidoreductase A (pPORA) during its posttranslational import into isolated barley chloroplasts. Protein purification and subsequent protein sequencing showed that the 16-kDa protein is an ortholog of a previously identified outer plastid envelope protein, Oep16. A protein of identical size was present in barley etioplasts and interacted with pPORA. Similar 16-kDa proteindependent crosslink products of pPORA were detected in wheat, pea, and Arabidopsis chloroplasts. Database analyses revealed that the 16-kDa protein belongs to a family of preprotein and amino acid transporters found in free-living bacteria and endosymbiotic mitochondria and chloroplasts. Antibodies raised against the 16-kDa protein inhibited import of pPORA, highlighting its role in protein import.

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Section: Resultsmentioning

confidence: 99%

“…Almost certainly, the 16-kDa protein is identical with Oep16. This protein had been proposed to form an amino acid-selective channel protein in the outer envelope of pea chloroplasts (39). The crosslinking (Figs.…”

Section: Discussionmentioning

confidence: 99%

The outer plastid envelope protein Oep16: Role as precursor translocase in import of protochlorophyllide oxidoreductase A

Reinbothe

Quigley

Springer

et al. 2004

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

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“…In this study, the seed-specific overexpression of a plasma membrane-localized amino acid permease in pea led to increased amino acid supply and OEP16 transcripts in embryos. Together with the in vitro selectivity of Ps-OEP16 for amino acids (36), it thus seems very likely that OEP16 is involved in amino acid transport across the outer envelope membrane of plastids. AroGP1 is a polygalacturonase converter, which is secreted to the apoplast and plays a role in regulating pectin metabolism during fruit ripening of tomato (46,47).…”

Section: Discussionmentioning

confidence: 99%

“…According to phenotype analysis of an OEP16.1 knockout line in Arabidopsis it was then postulated that OEP16 represents the translocation pore for PORA (25). Originally OEP16 was isolated as a transmembrane-spanning protein of 16 kDa from the outer envelope membrane of pea chloroplasts (36). When reconstituted into lipid bilayer membranes, the corresponding recombinant Ps-OEP16 protein formed a slightly cation-selective channel with transport selectivity for amino acids and amines.…”

mentioning

confidence: 99%

A search for factors influencing etioplast–chloroplast transition

Pudelski

Soll²,

Philippar³

2009

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

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“…HP20 itself or other PRAT proteins, such as HP22 or OEP16-1, 38 could serve as import channel. Alternatively, HP20 could insert into the outer envelope membrane spontaneously 39 or via an ankyrin-dependent mechanism 40,41 or could employ TOC75. 42 Work is in progress to explore these possibilities and further define the structure and function of the different PRAT proteins in mitochondria and chloroplasts.…”

Section: Summary and Perspectivesmentioning

confidence: 99%

New functions of the chloroplast Preprotein and Amino acid Transporter (PRAT) family members in protein import

Roßig

Reinbothe

Gray

et al. 2014

Plant Signaling & Behavior

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Common principles of protein translocation across membranesCells contain different, membrane-limited compartments endowed with specific proteins. To maintain these compartments, cells have developed elaborate systems for transporting the cell's few thousand different proteins to their final location. Export and import systems have been identified in bacteria and eukaryotes that operate by a similar set of principles.1 Each protein carries NH 2 -terminal or internal targeting information that is recognized by cytoplasmic targeting factors and directs the protein to specific receptors on the target membrane; the targeting signal interacts with a hetero-oligomeric trans-membrane channel that is gated both across and within the plane of the membrane. Molecular chaperones act as nucleoside triphosphate-powered import motors and interact with both the translocating polypeptide chain and the protein-conducting channel. Methods that have led to the identification of these principles include protein biochemistry, cell biology, and genetics.2-8 For example, it was found that mitochondria contain 2 types of receptors on their outer surface to bind cytosolic precursors for import. Mitochondrial precursors containing cleavable NH 2 -terminal pre-sequences interact with TOM20. By contrast, carrier proteins and other hydrophobic membrane proteins lacking cleavable NH 2 -terminal pre-sequences bind TOM70. A third TOM protein, TOM22, was found to associate with both TOM70 and TOM20. All 3 TOM proteins are essential for the formation of intact mitochondria and cooperate in the passage of precursors into the TOM40 import channel in the outer mitochondrial membrane.2-4 Import of pre-sequence-containing and pre-sequence-less precursors in fact converges at TOM40. 2-4Numerous other TOM proteins assist in subsequent steps of mitochondrial protein import. 2-4Import of pre-sequence-containing chloroplast precursors is mediated by at least 3 proteins: the 2 GTP binding receptors TOC159 and TOC34, and the β-barrel protein and translocation channel TOC75 5-8 . TOC159 and TOC34 are encoded by small gene families in Arabidopsis thaliana, with AtTOC159 containing 4 members, designated Attoc159, Attoc132, Attoc120, and Attoc90, and AtTOC34 containing 2 members, named Attoc34 and Attoc33. Biochemical and genetic evidence suggests that there is a functional specialization among the different members of the guanosine triphosphate hydrolyzing GTPase receptor families. 5-8Import of most pre-sequence-containing cytosolic precursors is Keywords: Membrane transport, Protein translocation, Chloroplasts and mitochondria, TIC and TIM translocons at the inner chloroplast envelope and inner mitochondrial membrane, TOC and TOM translocons at outer chloroplast and outer mitochondrial membrane, PRAT protein evolutionPlant cells contain distinct compartments such as the nucleus, the endomembrane system comprising the endoplasmic reticulum and Golgi apparatus, peroxisomes, vacuoles, as well as mitochondria and chloroplasts. All of these compartments are surroun...

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Isolation and characterization of an amino acid-selective channel protein present in the chloroplastic outer envelope membrane

Cited by 120 publications

References 52 publications

The outer plastid envelope protein Oep16: Role as precursor translocase in import of protochlorophyllide oxidoreductase A

The outer plastid envelope protein Oep16: Role as precursor translocase in import of protochlorophyllide oxidoreductase A

A search for factors influencing etioplast–chloroplast transition

New functions of the chloroplast Preprotein and Amino acid Transporter (PRAT) family members in protein import

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