Nanodomains of Cytochrome b  6  f and Photosystem II Complexes in Spinach Grana Thylakoid Membranes  . Issue 7 (17th July 2014)

• Record Type: Journal Article
• Authors: Johnson, Matthew P.; Vasilev, Cvetelin; Olsen, John D.; Hunter, C. Neil
• Is Part Of: The Plant Cell. Volume 26:Issue 7(2014)
• Page Start: 3051
• Page End: 3061
• Publication Date: 2014-07-17
• DOI: 10.1105/tpc.114.127233
• Languages: English
• ISSNs: 1040-4651

Abstract

Abstract : Colocalization of cytochrome b6 f and photosystem II complexes creates nanodomains that facilitate rapid exchange of the lipophilic electron carrier plastoquinone in the crowded thylakoid grana membrane. Abstract: The cytochrome b 6 f (cyt b 6 f ) complex plays a central role in photosynthesis, coupling electron transport between photosystem II (PSII ) and photosystem I to the generation of a transmembrane proton gradient used for the biosynthesis of ATP. Photosynthesis relies on rapid shuttling of electrons by plastoquinone (PQ ) molecules between PSII and cyt b 6 f complexes in the lipid phase of the thylakoid membrane. Thus, the relative membrane location of these complexes is crucial, yet remains unknown. Here, we exploit the selective binding of the electron transfer protein plastocyanin (Pc ) to the lumenal membrane surface of the cyt b 6 f complex using a Pc -functionalized atomic force microscope (AFM ) probe to identify the position of cyt b 6 f complexes in grana thylakoid membranes from spinach ( Spinacia oleracea ). This affinity-mapping AFM method directly correlates membrane surface topography with Pc -cyt b 6 f interactions, allowing us to construct a map of the grana thylakoid membrane that reveals nanodomains of colocalized PSII and cyt b6 f complexes. We suggest that the close proximity between PSII and cyt b 6 f complexes integrates solar energy conversion and electron transfer by fostering short-range diffusion of PQ in the protein-crowded thylakoid membrane, thereby optimizing photosynthetic efficiency.