Plastocyanin is the long-range electron carrier between photosystem II and photosystem I in plants

Abstract

<jats:p>In photosynthetic electron transport, large multiprotein complexes are connected by small diffusible electron carriers, the mobility of which is challenged by macromolecular crowding. For thylakoid membranes of higher plants, a long-standing question has been which of the two mobile electron carriers, plastoquinone or plastocyanin, mediates electron transport from stacked grana thylakoids where photosystem II (PSII) is localized to distant unstacked regions of the thylakoids that harbor PSI. Here, we confirm that plastocyanin is the long-range electron carrier by employing mutants with different grana diameters. Furthermore, our results explain why higher plants have a narrow range of grana diameters since a larger diffusion distance for plastocyanin would jeopardize the efficiency of electron transport. In the light of recent findings that the lumen of thylakoids, which forms the diffusion space of plastocyanin, undergoes dynamic swelling/shrinkage, this study demonstrates that plastocyanin diffusion is a crucial regulatory element of plant photosynthetic electron transport.</jats:p>

Stem Photosynthesis—A Key Element of Grass Pea (Lathyrus sativus L.) Acclimatisation to Salinity

“…The quantitative participation of Plastocyanin (PC) and an enzyme of the Calvin-Benson cycle (RuBisCo) were estimated by SDS-PAGE and immunoblotting in order to examine the effect of salinity on particular protein elements of the photosynthetic apparatus. PC, a small protein and long-range electron carrier between PSII and PSI [ 45 ], increased gradually with the increasing concentration of NaCl in both the leaves and stems of grass pea seedlings ( Figure 6 a). However, the increase of PC under 100 mM NaCl was threefold in leaves and almost fivefold in stems, as compared to organs in control conditions ( Figure 6 a).…”

Genetic analysis of the barley variegation mutant, grandpa1.a

“…Blue copper protein function as an electron shuffler in electron transfer reactions, such as biological nitrogen fixation, respiration and photosynthesis. Structure analysis indicated the putative blue copper proteins, G7, G9, G10, and G12, in the Gpa1 region contain a domain identified in plastocyanin, the long-range electron carrier between photosystems II and I [ 28 ]. Alternative oxidase is involved in the regulation of redox state of the electron transport chain in organelles [ 8 , 9 , 18 ].…”

Green Catalysts: Applied and Synthetic Photosynthesis

“…By building this biological/organic biohybrid, the work further demonstrated the feasibility of using synthetic biology methods to tether together and even redesign redox components to overcome diffusion-based rate limitations on electron transfer reactions [88]. More recently, it was observed that some of these diffusion limited reactions could be influenced in vivo by genetic manipulation of the grana diameter in the thylakoid membrane ultrastructure [89]. This work clearly demonstrated that plastocyanin diffusion to PSI becomes much slower if the grana diameter exceeds ∼500 nm.…”