Selective and specific degradation of the D 1 protein induced by binding of a novel Photosystem II inhibitor to the QB site

Inhibition of photosynthesis by excess excitation energy is initiated in the reaction center of photosystem II. The primary site of photoinhibition in the reaction center (components of primary charge separation or secondary electron acceptor Q B ) is still disputed. Photoinhibition is characterized by quenching of variable chlorophyll flurescence (F v ), resulting from increased thermal dissipation of excitation energy. Varying responses of initial fluorescence (F 0 ), however, seem to indicate involvement of different mechanisms. As far as photoinhibition is reversible within minutes to hours, it can be viewed as a controlled protective mechanism that serves to dissipate excessive energy, Supposedly, another dissipative mechanism, distinguished by its faster kinetics (response within seconds), is related to the energy‐dependent fluorescence quenching.

Photoinhibition

Heterolysis

Non-photochemical quenching

10.1111/j.1399-3054.1988.tb02020.x

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Citations (901)

Rapid interchange between two distinct forms of cyanobacterial photosystem II reaction-center protein D1 in response to photoinhibition.

Proceedings of the National Academy of Sciences (1993)

A. K. Clarke Arto Soitamo Petter Gustafsson Gunnar Öquist

We have studied photoinhibition of photosynthesis in the cyanobacterium Synechococcus sp. PCC 7942, which possesses two distinct forms of the photosystem II reaction-center protein D1 (D1:1 and D1:2). We report here that when cells adapted to a growth irradiance of 50 mumol.m-2.s-1 are exposed to an irradiance of 500 mumol.m-2.s-1, the normally predominant D1 form (D1:1) is rapidly replaced with the alternative D1:2. This interchange is not only complete within the first hour of photoinhibition but is also fully reversible once cells are returned to 50 mumol.m-2 x s-1. By using a mutant that synthesizes only D1:1, we show that the failure to replace D1:1 with D1:2 during photoinhibition results in severe loss of photosynthetic activity as well as a diminished capacity to recover after the stress period. We believe that this interchange between D1 forms may constitute an active component in a protection mechanism unique among photosynthetic organisms that enables cyanobacteria to effectively cope with and recover from photoinhibition.

Photoinhibition

10.1073/pnas.90.21.9973

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Citations (114)

In vivo and in vitro photoinhibition reactions generate similar degradation fragments of D1 and D2 photosystem‐II reaction‐centre proteins

European Journal of Biochemistry (1994)

Catherine A. Shipton James Barber

Isolation of photosystem-II reaction centres from pea leaves after photoinhibitory treatment at low temperature (0-1 degrees C) has provided evidence for the mechanism of degradation of the D1 protein in vivo. These isolated reaction centres did not appear to be spectrally distinct from preparations obtained from control leaves that had not been photoinhibited. Breakdown fragments of both the D1 and D2 proteins were, however, found in preparations isolated from photoinhibited leaves, and showed similarities with those detected when isolated reaction centres were exposed to acceptor-side photoinhibition. Analyses of the origin of D1 fragments indicated that the primary cleavage site of this protein was between transmembrane helices IV and V indicative of the acceptor-side mechanism for photoinhibition. The origins of other D1 protein fragments indicate that some donor-side photoinhibition may also have occurred in vivo under the conditions employed. We have shown that the spectral and functional integrating of the isolated photosystem II reaction centre complex is resistant to proteolytic cleavage by trypsin. Use of a more non-specific protease (subtilisin), however, caused significant destabilisation of the special pair of chlorophylls constituting the primary electron donor, P680, with a consequential loss of functional activity. Thus, it is possible that specific cleavage of photosystem-II reaction-centre proteins may occur in vivo following photoinhibitory damage without a significant change in structural integrity, a conclusion supported by the finding that photodamaged and normal reaction centres were isolated together.

Photoinhibition

P680

Cleavage (geology)

10.1111/j.1432-1033.1994.tb18682.x

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Citations (45)

PSI photoinhibition is more related to electron transfer from PSII to PSI rather than PSI redox state in Psychotria rubra

Photosynthesis Research (2016)

Wei Huang Yingjie Yang Jiao‐Lin Zhang Hong Hu Shi‐Bao Zhang

Photoinhibition

P700

DCMU

10.1007/s11120-016-0275-5

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Citations (27)

On the Mechanism of Photoinhibition in Chloroplasts. Relationship Between Changes in Fluorescence and Activity of Photosystem II

Journal of Plant Physiology (1990)

G. Heinrich Krause Susanne Somersalo Elisabeth Zumbusch Birgit Weyers Henrik Laasch

Photoinhibition

DCMU

Spinacia

Tricine

10.1016/s0176-1617(11)80038-6

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Citations (95)

The modification of chlorophyll fluorescence of Chlamydomonas reinhardtii by photoinhibition and chloramphenicol addition suggests a form of photosystem II less susceptible to degradation

FEBS Letters (1988)

Jean‐Marie Briantais Gabriel Cornic Michael Hodges

The effect of photoinhibition and chloramphenicol addition on room‐temperature chlorophyll fluorescence induction parameters exhibited by Chlamydomonas reinhardtii has been studied. The observed changes induced by these different treatments suggest the presence of a photosystem II (PS II) reaction centre having an abnormal turnover rate and which gives rise to the fast initital variable fluorescence rise ( F i − F o ) in the absence of DCMU. It is proposed that a pool of PS II with a modified D 1 protein exists which is less susceptible to degradation. Furthermore, it is shown that the fluorescence quenching associated with photoinhibition is not directly linked to PS II reaction centre degradation.

Photoinhibition

Chlamydomonas reinhardtii

DCMU

Chlamydomonas

Degradation

10.1016/0014-5793(88)80319-3

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Citations (28)