The Ribosome-Bound Protein Pam68 Promotes Insertion of Chlorophyll into the CP47 Subunit of Photosystem II

0489387 - MBÚ 2019 RIV US eng J - Journal Article
Bučinská, Lenka - Kiss, Eva - Koník, Peter - Knoppová, Jana - Komenda, Josef - Sobotka, Roman
The Ribosome-Bound Protein Pam68 Promotes Insertion of Chlorophyll into the CP47 Subunit of Photosystem II.
Plant Physiology. Roč. 176, č. 4 (2018), s. 2931-2942. ISSN 0032-0889. E-ISSN 1532-2548
R&D Projects: GA MŠMT(CZ) LO1416; GA MŠMT(CZ) ED2.1.00/19.0392
Institutional support: RVO:61388971
Keywords : SYNECHOCYSTIS SP PCC-6803 * SP PCC 6803 * ESCHERICHIA-COLI
OECD category: Microbiology
Impact factor: 6.305, year: 2018

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.
Permanent Link: http://hdl.handle.net/11104/0283817