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High-light versus low-light: Effects on paired photosystem II supercomplex structural rearrangement in pea plants

DOI: 10.3390/ijms21228643 DOI Help

Authors: Alessandro Grinzato (University of Padova) , Pascal Albanese (Politecnico di Torino) , Roberto Marotta (IstitutoItaliano di Tecnologia—IIT) , Paolo Swuec (University of Milano; Human Technopole) , Guido Saracco (Politecnico di Torino) , Martino Bolognesi (University of Milano) , Giuseppe Zanotti (University of Padova) , Cristina Pagliano (Politecnico di Torino)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: International Journal Of Molecular Sciences , VOL 21

State: Published (Approved)
Published: November 2020
Diamond Proposal Number(s): 19714

Open Access Open Access

Abstract: In plant grana thylakoid membranes Photosystem II (PSII) associates with a variable number of antenna proteins (LHCII) to form different types of supercomplexes (PSII-LHCII), whose organization is dynamically adjusted in response to light cues, with the C2S2 more abundant in high-light and the C2S2M2 in low-light. Paired PSII-LHCII supercomplexes interacting at their stromal surface from adjacent thylakoid membranes were previously suggested to mediate grana stacking. Here, we present the cryo-electron microscopy maps of paired C2S2 and C2S2M2 supercomplexes isolated from pea plants grown in high-light and low-light, respectively. These maps show a different rotational offset between the two supercomplexes in the pair, responsible for modifying their reciprocal interaction and energetic connectivity. This evidence reveals a different way by which paired PSII-LHCII supercomplexes can mediate grana stacking at diverse irradiances. Electrostatic stromal interactions between LHCII trimers almost completely overlapping in the paired C2S2 can be the main determinant by which PSII-LHCII supercomplexes mediate grana stacking in plants grown in high-light, whereas the mutual interaction of stromal N-terminal loops of two facing Lhcb4 subunits in the paired C2S2M2 can fulfil this task in plants grown in low-light. The high-light induced accumulation of the Lhcb4.3 protein in PSII-LHCII supercomplexes has been previously reported. Our cryo-electron microscopy map at 3.8 Å resolution of the C2S2 supercomplex isolated from plants grown in high-light suggests the presence of the Lhcb4.3 protein revealing peculiar structural features of this high-light-specific antenna important for photoprotection.

Journal Keywords: cryo-electron microscopy; light acclimation; photosystem II supercomplex; plant thylakoid membranes

Subject Areas: Biology and Bio-materials

Diamond Offline Facilities: Electron Bio-Imaging Centre (eBIC)
Instruments: Krios III-Titan Krios III at Diamond


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