Higher Plant Photosystem II Light-Harvesting Antenna, Not the Reaction Center, Determines the Excited-State Lifetime — Both the Maximum and the Nonphotochemically Quenched (CROSBI ID 185141)
Prilog u časopisu | izvorni znanstveni rad | međunarodna recenzija
Podaci o odgovornosti
Belgio, Erica ; Johnson, Matthew P. ; Jurić, Snježana ; Ruban, Alexander V.
engleski
Higher Plant Photosystem II Light-Harvesting Antenna, Not the Reaction Center, Determines the Excited-State Lifetime — Both the Maximum and the Nonphotochemically Quenched
The maximum chlorophyll fluorescence lifetime in isolated photosystem II (PSII) light-harvesting complex (LHCII) antenna is 4 ns ; however, it is quenched to 2 ns in intact thylakoid membranes when PSII reaction centers (RCIIs) are closed (Fm). It has been proposed that the closed state of RCIIs is responsible for the quenching. We investigated this proposal using a new, to our knowledge, model system in which the concentration of RCIIs was highly reduced within the thylakoid membrane. The system was developed in Arabidopsis thaliana plants under long-term treatment with lincomycin, a chloroplast protein synthesis inhibitor. The treatment led to 1), a decreased concentration of RCIIs to 10% of the control level and, interestingly, an increased antenna component ; 2), an average reduction in the yield of photochemistry to 0.2 ; and 3), an increased nonphotochemical chlorophyll fluorescence quenching (NPQ). Despite these changes, the average fluorescence lifetimes measured in Fm and Fm′ (with NPQ) states were nearly identical to those obtained from the control. A 77 K fluorescence spectrum analysis of treated PSII membranes showed the typical features of preaggregation of LHCII, indicating that the state of LHCII antenna in the dark-adapted photosynthetic membrane is sufficient to determine the 2 ns Fm lifetime. Therefore, we conclude that the closed RCs do not cause quenching of excitation in the PSII antenna, and play no role in the formation of NPQ.
NPQ ; fluorescence lifetime ; PSII
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Podaci o izdanju
102 (12)
2012.
2761-2771
objavljeno
0006-3495
1542-0086
10.1016/j.bpj.2012.05.004