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Isolated plant mitochondria import chloroplast precursor proteins in vitro with the same efficiency as chloroplasts
- Source :
- The Journal of biological chemistry. 277(7)
- Publication Year :
- 2001
-
Abstract
- Most chloroplast and mitochondrial proteins are synthesized with N-terminal presequences that direct their import into the appropriate organelle. In this report we have analyzed the specificity of standard in vitro assays for import into isolated pea chloroplasts and mitochondria. We find that chloroplast protein import is highly specific because mitochondrial proteins are not imported to any detectable levels. Surprisingly, however, pea mitochondria import a range of chloroplast protein precursors with the same efficiency as chloroplasts, including those of plastocyanin, the 33-kDa photosystem II protein, Hcf136, and coproporphyrinogen III oxidase. These import reactions are dependent on the Deltaphi across the inner mitochondrial membrane, and furthermore, marker enzyme assays and Western blotting studies exclude any import by contaminating chloroplasts in the preparation. The pea mitochondria specifically recognize information in the chloroplast-targeting presequences, because they also import a fusion comprising the presequence of coproporphyrinogen III oxidase linked to green fluorescent protein. However, the same construct is targeted exclusively into chloroplasts in vivo indicating that the in vitro mitochondrial import reactions are unphysiological, possibly because essential specificity factors are absent in these assays. Finally, we show that disruption of potential amphipathic helices in one presequence does not block import into pea mitochondria, indicating that other features are recognized.
- Subjects :
- Chlorophyll
Chloroplasts
Photosystem II
Recombinant Fusion Proteins
Blotting, Western
Green Fluorescent Proteins
Biology
Mitochondrion
Biochemistry
Green fluorescent protein
Organelle
Protein Precursors
Inner mitochondrial membrane
Molecular Biology
Plastocyanin
Plant Physiological Phenomena
Coproporphyrinogen III oxidase
Arabidopsis Proteins
Coproporphyrinogen Oxidase
Peas
food and beverages
Membrane Proteins
Cell Biology
Mitochondria
Protein Structure, Tertiary
Chloroplast
Luminescent Proteins
Protein Transport
Microscopy, Fluorescence
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 277
- Issue :
- 7
- Database :
- OpenAIRE
- Journal :
- The Journal of biological chemistry
- Accession number :
- edsair.doi.dedup.....d1bdc739f68e590d193c245f5ef9e4eb