Le Labex Dynamo
2018 Buchert et al.
The labile interactions of cyclic electron flow effector proteins.
Buchert et al.; J. Biol. Chem. 2018
The suprmolecular organization of membrane proteins (MP) is sensitive to environmental changes in photosynthetic organisms. Isolation of MP supercomplexes from the green algae Chlamydomonas reinhardtii, which are believed to contribute to cyclic electron flow (CEF) between the cytochrome b6f complex (Cyt-b6f) and photosystem I (PSI), proved difficult. In our hands, poor retention of the Cyt-b6f together with PSI in heavy sucrose density gradient (SDG) fractions was a crucial obstacle to isolate the elusive CEF supercomplex, even upon using chemical crosslinkers or amphipol substitution of detergents. Assisted by indepedent affinity purification and mass spectometry approaches, we utilized disintegrating MP assemblies and demonstrated that the algal-specific CEF effector proteins PETO and ANR1 are bona fide Cyt-b6f interactors, with ANR requiring the presence of an additional, presently unknown, protein. We narrowed down the Cyt-b6f interface where PETO is loosely attached to cytochrome f and to a stromal region of subnuit IV, which also contains phosphorylation sites for the STT7 kinase.
Publié le : 10/01/2019