A Study of State Changes in Chlorella: The Effect of Uncoupler and Energy Transfer Inhibitors

Sane, P. V.; Furtado, D.; Desai, T. S.; Tatake, V. G.

doi:10.1515/znc-1982-5-618

Cited by 7 publications

(8 citation statements)

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“…A controversy has arisen in the past whether the darkadapted state in various organisms is state I or state II (16,17,19,21,25,75). We have observed pronounced variations in the amplitudes of the two decay components associated with lifetimes of >300 (T2) and 600 ps (T3), respectively, at the Fo level.…”

Section: State Transitions and A4-heterogeneitymentioning

confidence: 77%

“…State transitions have recently been studied in green algae (19-23) and in leaves and chloroplasts of higher plants ( [24][25][26][27]. The characteristics of these transitions are changes in oxygen evolution efficiency (16,28,29), in chlorophyll (Chl) fluorescence induction curves (20-22, 30, 31), and in the far-red/red ratio in low temperature Chl fluorescence (17,19,21,32). The current explanation of these processes in higher plants and green algae involves a redistribution of light energy between PS II and PS I brought about by reversible phosphorylation of the light-harvesting complex (LHCP) (18,22,(32)(33)(34)(35).…”

Section: Introductionmentioning

confidence: 99%

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State Transitions in the Green Alga Scenedesmus Obliquus Probed by Time-Resolved Chlorophyll Fluorescence Spectroscopy and Global Data Analysis

Wendler¹,

Holzwarth²

1987

Biophysical Journal

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Decay-associated fluorescence spectra of the green alga Scenedesmus obliquus have been measured by single-photon timing with picosecond resolution in various states of light adaptation. The data have been analyzed by applying a global data analysis procedure. The amplitudes of the decay-associated spectra allow a determination of the relative antenna sizes of the photosystems. We arrive at the following conclusions: (a) The fluorescence kinetics of algal cells with open PS II centers (F(0) level) have to be described by a sum of three exponential components. These decay components are attributed to photosystem (PS) I (tau approximately 85 ps, lambda(max) (em) approximately 695-700 nm), open PS II alpha-centers (tau approximately 300 ps, lambda(max) (em) = 685 nm), and open PS II beta-centers (tau approximately 600 ps, lambda(max) (em) = 685 nm). A fourth component of very low amplitude (tau approximately 2.2-2.3 ns, lambda(max) (em) = 685 nm) derives from dead chlorophyll. (b) At the F(max) level of fluorescence there are also three decay components. They originate from PS I with properties identical to those at the F(0) level, from closed PS II alpha-centers (tau approximately 2.2 ns, lambda(max) (em) = 685 nm) and from closed PS beta-centers (tau approximately 1.2 ns, lambda(max) (em) = 685 nm). (c) The major effect of light-induced state transitions on the fluorescence kinetics involves a change in the relative antenna size of alpha- and beta-units brought about by the reversible migration of light-harvesting complexes between alpha-centers and beta-centers. (d) A transition to state II does not measurably increase the direct absorption cross-section (antenna size) of PS I. Our data can be rationalized in terms of a model of the antenna organization that relates the effects of state transitions and light-harvesting complex phosphorylation with the concepts of PS II alpha,beta-heterogeneity. We discuss why our results are in disagreement with those of a recent lifetime study of Chlorella by M. Hodges and I. Moya (1986, Biochim. Biophys. Acta., 849:193-202).

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Section: State Transitions and A4-heterogeneitymentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

State Transitions in the Green Alga Scenedesmus Obliquus Probed by Time-Resolved Chlorophyll Fluorescence Spectroscopy and Global Data Analysis

Wendler¹,

Holzwarth²

1987

Biophysical Journal

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“…The first relates to the finding that the slow light-driven fluorescence increases of the type illustrated in Fig. 2 are abolished by the addition of uncouplers and ATPase inhibitors (Papageorgiou and Govindjee, 1968a;Sane et al, 1982;Cart et al, 1984a) conditions which might be expected to prevent LHC-II phosphorylation. Following the addition of such agents, the value of FM normally falls back to that of the dark-adapted state.…”

Section: Lhc-ii Phosphorylation In Green Algaementioning

confidence: 99%

State 1/State 2 changes in higher plants and algae

1987

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Current ideas regarding the molecular basis of State 1/State 2 transitions in higher plants and green algae are mainly centered around the view that excitation energy distribution is controlled by phosphorylation of the light-harvesting complex of photosystem II (LHC-II). The evidence supporting this view is examined and the relationship of the transitions occurring in these systems to the corresponding transitions seen in red and blue-green algae is explored.

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“…Reversal to State 1 seems to be achieved by dephosphorylation of LHCP through the action of a membrane-bound phosphatase and occurs when the PQ pool is oxidized by excess PSI light or by a prolonged dark treatment (8,16,25). However, Sane et al (24) have questioned this mechanism in Chlorella and suggest that redox changes may be wholly responsible for State 2 development.…”

mentioning

confidence: 99%

“…Therefore, it is reasonable to assume that phosphorylation of LHCP can cause a reduction in the absorption cross-section of PSII. Studies involving the measurement of low temperature emission (5), enhancement (24), and electron transport (1 1) indicate that the reduction in the photoactivation of PSII by LHCP phosphorylation is paralleled by an increase in PSI activity which must therefore be due to an increase in absorption cross-section of PSI. The effect of phosphorylation on the Fv/Fm ratio and Am.…”

mentioning

confidence: 99%

State 1-State 2 Transitions in a Unicellular Green Algae

Hodges¹,

Barber²

1983

Plant Physiol.

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A study has been made on the State 1-State 2 transitions exhibited by the unicellular green algae Chlore&apyrenoidosa. ChlorophyUl fluorescence induction curves from algae adapted to State 1 or State 2 have been analyzed and a comparison made with similar curves produced by decreasing the intensity of light going to the photosystem II reaction centers. In both cases, quenching of the maximum fluorescence yield (Fm) and the initial fluorescence yield (F.) were observed so that the Fvs/Fm ratio and the area above the induction curve (A,,.,) remained constant. The State 1-State 2 transition also produced changes in the 8,B component indicative of some alteration within photosystem II organization. The implications of these experiments on the in vivo mechanism for energy redistribution between the two photosystems are discussed in terms of changes in absorption cross-section rather than being due to spillover from photosystem II to photosystem L. These changes may reflect the phosphorylation of the light-harvesting chlorophyll a/b protein complex and its subsequent migration away from the photosystem II core leading to its closer association with photosystem I.To maintain maximal rates of photosynthesis at limiting light intensities, plants have evolved a mechanism which enables them to optimize the balance of incoming light energy between PSI and PSII (21). The first clear demonstration of the regulatory mechanism was made by Bonaventura and Myers (7) using Chlorella pyrenoidosa. They showed that when this alga was exposed to light preferentially absorbed by PSII there was a slow readjustment in its distribution to PSI with the overall effect of increasing the quantum yield for 02 evolution and decreasing the yield of Chl fluorescence. This readjustment in energy distribution from PSII to PSI was termed a State 1 to State 2 transition. The reversal of the transition was accomplished by illuminating with excess PSI light or by subjecting the organisms to a prolonged dark treatment.The State 1-State 2 phenomenon is now well established as a physiological mechanism found in a wide range of systems including higher plant leaves (6,10,23 the details ofthe molecular mechanisms involved in this regulatory mechanism. There is a requirement for the presence of the LHCP3 for higher plants and green algae (10) although in red algae and cyanobacteria the State 1-State 2 transition occurs even though LHCP is not present. However, recently small changes in 77K fluorescence spectra indicative of State transitions have been seen in a Chl b-less mutant of Scenedesmus. For many years there were hints, based on studies with isolated thylakoids, that the control mechanism involved changes in cation levels within chloroplast (2). More recently it has been suggested that the reversible phosphorylation of the LHCP is the basis of the State 1-State 2 mechanism (1,5,16,25). Convincing work with isolated thylakoids has shown how the kinase responsible for LHCP phosphorylation is activated when the PQ pool is over reduced (15). Suc...

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A Study of State Changes in Chlorella: The Effect of Uncoupler and Energy Transfer Inhibitors

Cited by 7 publications

References 0 publications

State Transitions in the Green Alga Scenedesmus Obliquus Probed by Time-Resolved Chlorophyll Fluorescence Spectroscopy and Global Data Analysis

State Transitions in the Green Alga Scenedesmus Obliquus Probed by Time-Resolved Chlorophyll Fluorescence Spectroscopy and Global Data Analysis

State 1/State 2 changes in higher plants and algae

State 1-State 2 Transitions in a Unicellular Green Algae

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