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 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.
Mesh Terms:
Arabidopsis Proteins, Cell Membrane, Chloroplast Proteins, Chloroplasts, Cloning, Molecular, Guanosine Triphosphate, Hydrolysis, Models, Biological, Peas, Protein Binding, Protein Interaction Mapping, Protein Structure, Tertiary, Protein Transport, Recombinant Proteins, Signal Recognition Particle, Thylakoids
Arabidopsis Proteins, Cell Membrane, Chloroplast Proteins, Chloroplasts, Cloning, Molecular, Guanosine Triphosphate, Hydrolysis, Models, Biological, Peas, Protein Binding, Protein Interaction Mapping, Protein Structure, Tertiary, Protein Transport, Recombinant Proteins, Signal Recognition Particle, Thylakoids
J. Biol. Chem.
Date: Oct. 29, 2010
PubMed ID: 20729200
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