A Dynamic cpSRP43-Albino3 Interaction Mediates Translocase Regulation of Chloroplast Signal Recognition Particle (cpSRP)-targeting Components

The chloroplast signal recognition particle (cpSRP) and its receptor, chloroplast FtsY (cpFtsY), form an essential complex with the translocase Albino3 (Alb3) during post-translational targeting of light-harvesting chlorophyll-binding proteins (LHCPs). Here, we describe a combination of studies that...

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Bibliographic Details
Published in:The Journal of biological chemistry 2010-10, Vol.285 (44), p.34220-34230
Main Authors: Lewis, Nathaniel E., Marty, Naomi J., Kathir, Karuppanan Muthusamy, Rajalingam, Dakshinamurthy, Kight, Alicia D., Daily, Anna, Kumar, Thallapuranam Krishnaswamy Suresh, Henry, Ralph L., Goforth, Robyn L.
Format: Article
Language:English
Subjects:
Albino3
Arabidopsis Proteins - metabolism
Cell Membrane - metabolism
Chloroplast
Chloroplast Proteins
Chloroplasts - metabolism
Cloning, Molecular
GTP Regulation
Guanosine Triphosphate - chemistry
Hydrolysis
Membrane Biology
Membrane Proteins
Membrane Targeting
Models, Biological
Pisum sativum - metabolism
Plant Biology
Protein Binding
Protein Interaction Mapping
Protein Structure, Tertiary
Protein Targeting
Protein Translocation
Protein Transport
Protein-Protein Interactions
Recombinant Proteins - chemistry
Signal Recognition Particle
Signal Recognition Particle - metabolism
Thylakoids - metabolism
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Summary:The chloroplast signal recognition particle (cpSRP) and its receptor, chloroplast FtsY (cpFtsY), form an essential complex with the translocase Albino3 (Alb3) during post-translational targeting of light-harvesting chlorophyll-binding proteins (LHCPs). Here, we describe a combination of studies that explore the binding interface and functional role of a previously identified cpSRP43-Alb3 interaction. Using recombinant proteins corresponding to the C terminus of Alb3 (Alb3-Cterm) and various domains of cpSRP43, we identify the ankyrin repeat region of cpSRP43 as the domain primarily responsible for the interaction with Alb3-Cterm. Furthermore, we show Alb3-Cterm dissociates a cpSRP·LHCP targeting complex in vitro and stimulates GTP hydrolysis by cpSRP54 and cpFtsY in a strictly cpSRP43-dependent manner. These results support a model in which interactions between the ankyrin region of cpSRP43 and the C terminus of Alb3 promote distinct membrane-localized events, including LHCP release from cpSRP and release of targeting components from Alb3.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M110.160093