The thylakoid membrane protein ALB3 associates with the cpSecY-translocase in Arabidopsis thaliana

The integration of light-harvesting chlorophyll proteins (LHCPs) into the thylakoid membrane requires the integral thylakoid membrane protein ALB3, a homologue of the bacterial cytoplasmic membrane protein YidC. In bacteria, YidC is associated with the SecY-translocase and facilitates the integratio...

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Bibliographic Details
Published in:Biochemical journal 2002-12, Vol.368 (Pt 3), p.777-781
Main Authors: Klostermann, Eva, Droste Gen Helling, Imke, Carde, Jean-Pierre, Schünemann, Danja
Format: Article
Language:English
Subjects:
Arabidopsis - metabolism
Arabidopsis Proteins - chemistry
Arabidopsis Proteins - metabolism
Chloroplast Proteins
Chloroplasts - metabolism
Chromatography, Gel
Cross-Linking Reagents - pharmacology
DNA, Complementary - metabolism
Electrophoresis, Polyacrylamide Gel
Immunohistochemistry
Light-Harvesting Protein Complexes
Membrane Proteins - metabolism
Microscopy, Electron
Photosynthetic Reaction Center Complex Proteins - metabolism
Precipitin Tests
Protein Binding
Protein Transport
SEC Translocation Channels
Thylakoids - metabolism
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Summary:The integration of light-harvesting chlorophyll proteins (LHCPs) into the thylakoid membrane requires the integral thylakoid membrane protein ALB3, a homologue of the bacterial cytoplasmic membrane protein YidC. In bacteria, YidC is associated with the SecY-translocase and facilitates the integration of Sec-dependent proteins into the plasma membrane. In addition, it is also involved in the insertion of Sec-independent proteins. In the present study we demonstrate, in Arabidopsis thaliana, that most ALB3 is a constituent of an oligomeric complex of approx. 180 kDa. In addition, we detected ALB3 in several higher-molecular-mass complexes (up to 700 kDa). Furthermore, we show that most ALB3 co-fractionates with cpSecY during gel-filtration analysis and blue native gel electrophoresis, suggesting an association of ALB3 with the cpSecY complex. A direct interaction of ALB3 with the cpSecY complex was demonstrated by co-immunoprecipitation experiments using digitonin-solubilized thylakoid membrane proteins and anti-cpSecY or anti-ALB3 antibodies. This result was further confirmed by electron microscopic co-immunolocalization of ALB3 and cpSecY. In addition, an association of ALB3 with the cpSecY complex was demonstrated directly by cross-linking experiments using the chemical cross-linker disuccinimidyl suberate.
ISSN:0264-6021
1470-8728
DOI:10.1042/BJ20021291