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The Ribosome-Bound Protein Pam68 Promotes Insertion of Chlorophyll into the CP47 Subunit of Photosystem II.
- Source :
-
Plant physiology [Plant Physiol] 2018 Apr; Vol. 176 (4), pp. 2931-2942. Date of Electronic Publication: 2018 Feb 20. - Publication Year :
- 2018
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Abstract
- Photosystem II (PSII) is a large enzyme complex embedded in the thylakoid membrane of oxygenic phototrophs. The biogenesis of PSII requires the assembly of more than 30 subunits, with the assistance of a number of auxiliary proteins. In plants and cyanobacteria, the photosynthesis-affected mutant 68 (Pam68) is important for PSII assembly. However, its mechanisms of action remain unknown. Using a Synechocystis PCC 6803 strain expressing Flag-tagged Pam68, we purified a large protein complex containing ribosomes, SecY translocase, and the chlorophyll-binding PSII inner antenna CP47. Using 2D gel electrophoresis, we identified a pigmented Pam68-CP47 subcomplex and found Pam68 bound to ribosomes. Our results show that Pam68 binds to ribosomes even in the absence of CP47 translation. Furthermore, Pam68 associates with CP47 at an early phase of its biogenesis and promotes the synthesis of this chlorophyll-binding polypeptide until the attachment of the small PSII subunit PsbH. Deletion of both Pam68 and PsbH nearly abolishes the synthesis of CP47, which can be restored by enhancing chlorophyll biosynthesis. These results strongly suggest that ribosome-bound Pam68 stabilizes membrane segments of CP47 and facilitates the insertion of chlorophyll molecules into the translated CP47 polypeptide chain.<br /> (© 2018 American Society of Plant Biologists. All Rights Reserved.)
- Subjects :
- Bacterial Proteins genetics
Cell Membrane metabolism
Electrophoresis, Gel, Two-Dimensional
Light-Harvesting Protein Complexes genetics
Mutation
Phosphoproteins genetics
Phosphoproteins metabolism
Photosystem II Protein Complex genetics
Protein Binding
Synechocystis genetics
Synechocystis metabolism
Bacterial Proteins metabolism
Chlorophyll metabolism
Light-Harvesting Protein Complexes metabolism
Photosystem II Protein Complex metabolism
Ribosomes metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1532-2548
- Volume :
- 176
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Plant physiology
- Publication Type :
- Academic Journal
- Accession number :
- 29463774
- Full Text :
- https://doi.org/10.1104/pp.18.00061