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PsbS protein modulates non-photochemical chlorophyll fluorescence quenching in membranes depleted of photosystems

Paper ID Volume ID Publish Year Pages File Format Full-Text
29657 44427 2015 7 PDF Available
Title
PsbS protein modulates non-photochemical chlorophyll fluorescence quenching in membranes depleted of photosystems
Abstract

•NPQ in lincomycin-grown plants was found to depend upon PsbS protein.•NPQ in chloroplasts of the plants overexpressing PsbS reached 7.•The NPQ state revealed a large 700 nm fluorescence peak of aggregated LHCII.•PsbS concentration did not affect fluorescence lifetimes in the Fm state.

Plants with varying levels of PsbS protein were grown on lincomycin. Enhanced levels of non-photochemical fluorescence quenching (NPQ) in over-expressers of the protein have been observed. This was accompanied by increased amplitude of the irreversible NPQ component, qI, previously considered to reflect mainly photoinhibition of PSII reaction centres (RCII). However, since RCIIs were largely absent the observed qI is likely to originate from the LHCII antenna. In chloroplasts of over-expressers of PsbS grown on lincomycin an abnormally large NPQ (∼7) was characterised by a 0.34 ns average chlorophyll fluorescence lifetime. Yet the lifetime in the Fm state was similar to that of wild-type plants. 77 K fluorescence emission spectra revealed a specific 700 nm peak typical of LHCII aggregates as well as quenching of the PSI fluorescence at 730 nm. The aggregated state manifested itself as a clear change in the distance between LHCII complexes detected by freeze-fracture electron microscopy. Grana thylakoids in the quenched state revealed 3 times more aggregated LHCII particles compared to the dark-adapted state. Overall, the results directly demonstrate the importance of LHCII aggregation in the NPQ mechanism and show that the PSII supercomplex structure plays no role in formation of the observed quenching.

Keywords
ETC, electron transport chain; FFEM, freeze-fracture electron microscopy; IRF, instrument response function; L17, PsbS overexpressor; LHCII, light harvesting antenna; NPQ, non-photochemical chlorophyll fluorescence quenching; npq4, PsbS knockout; PSII, ph
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PsbS protein modulates non-photochemical chlorophyll fluorescence quenching in membranes depleted of photosystems
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 152, Part B, November 2015, Pages 301–307
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us