Proceedings of the National Academy of Sciences - PNAS, 2000-02, Vol.97 (4), p.1926-1931
2000
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Details
- Autor(en) / Beteiligte
- Titel
- A Novel Precursor Recognition Element Facilitates Posttranslational Binding to the Signal Recognition Particle in Chloroplasts
- Ist Teil von
- Proceedings of the National Academy of Sciences - PNAS, 2000-02, Vol.97 (4), p.1926-1931
- Ort / Verlag
- United States: National Academy of Sciences of the United States of America
- Erscheinungsjahr
- 2000
- Quelle
- MEDLINE
- Beschreibungen/Notizen
- Signal recognition particles (SRPs) in the cytosols of prokaryotes and eukaryotes are used to target proteins to cytoplasmic membranes and the endoplasmic reticulum, respectively. The mechanism of targeting relies on cotranslational SRP binding to hydrophobic signal sequences. An organellar SRP identified in chloroplasts (cpSRP) is unusual in that it functions posttranslationally to localize a subset of nuclear-encoded thylakoid proteins. In assays that reconstitute thylakoid integration of the light harvesting chlorophyll-binding protein (LHCP), stromal cpSRP binds LHCP posttranslationally to form a cpSRP/LHCP transit complex, which is believed to represent the LHCP form targeted to thylakoids. In this investigation, we have identified an 18-aa sequence motif in LHCP (L18) that, along with a hydrophobic domain, is required for transit complex formation. Fusion of L18 to the amino terminus of an endoplasmic reticulum-targeted protein, preprolactin, led to transit complex formation whereas wild-type preprolactin exhibited no ability to form a transit complex. In addition, a synthetic L18 peptide, which competed with LHCP for transit complex formation, caused a parallel inhibition of LHCP integration. Translocation of proteins by the thylakoid Sec and Delta pH transport systems was unaffected by the highest concentration of L18 peptide examined. Our data indicate that a motif contained in L18 functions in precursor recruitment to the posttranslational SRP pathway, one of at least four different thylakoid sorting pathways used by chloroplasts.
- Sprache
- Englisch
- Identifikatoren
- ISSN: 0027-8424eISSN: 1091-6490DOI: 10.1073/pnas.030395197Titel-ID: cdi_pubmedcentral_primary_oai_pubmedcentral_nih_gov_26538
- Format
- –
- Schlagworte
- Amino Acid Sequence, Amino acids, Antibodies, Binding, Competitive, Biological Sciences, Biological Transport, Biology, Chloroplasts, Chloroplasts - metabolism, Clines, Delta protein, Endoplasmic Reticulum - metabolism, Flowers & plants, Gels, light harvesting chlorophyll-binding protein, Light-Harvesting Protein Complexes, Molecular Sequence Data, Open reading frames, Peptide Fragments - pharmacology, Peptides, Photosynthetic Reaction Center Complex Proteins - genetics, Photosynthetic Reaction Center Complex Proteins - metabolism, preprolactin, Prolactin - metabolism, Protein Binding, Protein precursors, Protein Precursors - metabolism, Protein Processing, Post-Translational, Protein Sorting Signals - metabolism, Proteins, Receptors, Recombinant Proteins, Saccharomyces cerevisiae Proteins, Sec protein, Signal Recognition Particle - metabolism, Thylakoids, Thylakoids - metabolism