On the participation of chloride in bicarbonate‐induced reversal of anion inhibition of photosystem II electron transport in spinach thylakoids

Jajoo, Anjana; Bharti, Sudhakar

doi:10.1111/j.1399-3054.1993.tb01763.x

Cited by 7 publications

(3 citation statements)

References 35 publications

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“…Rates obtained in heat-treated thylakoid membranes were 3-5% of control values suggesting that the OEC was almost completely inactivated in heat-treated thylakoid membranes. Effects of anion were observed equally well in heat-shocked thylakoids that are known to have lost the ability to evolve oxygen and so the action of anions was suggested to be on the acceptor side of PS II (Jajoo and Bharti 1993b). However in case of oxalate, inhibition of PS II activity was not observed in DPC ?…”

Section: Effects Of Oxalate On Ps IImentioning

confidence: 94%

Elucidating the site of action of oxalate in photosynthetic electron transport chain in spinach thylakoid membranes

et al. 2008

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The effects of oxalate on PS II and PS I photochemistry were studied. The results suggested that in chloride-deficient thylakoid membranes, oxalate inhibited activity of PS II as well as PS I. To our knowledge, this is the only anion so far known which inhibits both the photosystems. Measurements of fluorescence induction kinetics, YZ* decay, and S2 state multiline EPR signal suggested that oxalate inhibited PS II at the donor side most likely on the oxygen evolving complex. Measurements of re-reduction of P700+ signal in isolated PS I particles in oxalate-treated samples suggested a binding site of oxalate on the donor, as well as the acceptor side of PS I.

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Section: Effects Of Oxalate On Ps IImentioning

confidence: 94%

Elucidating the site of action of oxalate in photosynthetic electron transport chain in spinach thylakoid membranes

et al. 2008

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“…The order of effectiveness of various anions in substituting for Clwas Br -> I -> F -> NO 2 -~ PO 4 3-> HCO 3 -. In our earlier work (Jajoo and Bharti 1993), besides the water oxidation site, Clwas suggested to have a site of action between Q A and Q B . Vliet and Rutherford (1996) observed distinct Cl --depletion effects in PS2 observed under two different Cl --depletion treatments indicating the presence of two distinct binding sites in PS2.…”

mentioning

confidence: 92%

Decay Kinetics of Tyrosine Radical (Y<sub>Z</sub><sup>*</sup>) in Chloride Anion-Depleted Photosystem 2 Studied by Time-Resolved EPR

Jajoo¹,

Bharti²,

Kawamori³

2004

Photosynt.

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The decay of tyrosine cation radical was found to be biphasic at 253 K. The fast phase corresponds to the Y Z• component while the slow phase corresponds to the tyrosine D radical (Y D • ) component. At 253 K, the t 1/2 value was ~28.6 s for the fast phase and ~190.7 s for the slow phase. The fast phase is attributed to the recombination of charges between Y Z• and Q A -. The activation energy for the reaction of Y Z with Q A between 253 and 293 K was 48 kJ mol -1 in Cl --depleted photosystem 2 (PS2) membranes. Both the decay rate and the amplitude of the PAR -induced signal of Y Z• were affected by addition of chloride anion. Change in the decay rate and the amplitude of the PAR-induced signal of Y Z• was observed when other anions like Br -, I -, F, HCO 3 -, NO 3 -, PO 4 3were substituted in the Cl --depleted PS2.

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“…It has been reported earlier that the inhibition induced by formate or nitrite can be overcome by bicarbonate (Stemler and Murphy 1985, van Rensen et al 1999). Further, Jajoo and Bharti (1993) showed that the presence of chloride lowers the amount of bicarbonate required to overcome the inhibition induced by nitrite or formate. Loss of S 2 state multiline signal (Jajoo et al 2005) and changes observed in the thermoluminescence studies (Sahay et al 2006b) in nitrite‐treated samples have shown that nitrite probably acts on the donor side of PS II.…”

Section: Introductionmentioning

confidence: 99%

Relation between the mode of binding of nitrite and the energy distribution between the two photosystems

Singh

Jajoo

Sahay

et al. 2007

Physiologia Plantarum

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The reversibility of nitrite‐induced inhibition in relation to energy distribution between the two photosystems was studied in spinach thylakoid membranes. Measurements of electron transfer rate catalyzed by photosystem I (PS I) and photosystem II (PS II), chlorophyll a (Chl a) fluorescence induction kinetics, S2 state multiline spectra, and room temperature electron paramagnetic resonance (EPR) signals indicated that nitrite anions bind PS II in two ways: dissociable (loose) and non‐dissociable (tight). The inhibition caused by the dissociable binding was reversible in washed (nitrite‐treated samples washed with nitrite‐free medium) samples, while the inhibition caused by the non‐dissociable binding was irreversible. At 77 K, an increase in absorption cross section of PS I (as inferred from the excitation spectra of Chl a fluorescence) and a decrease in absorption cross section of PS II in nitrite‐treated sample when compared with sample washed with nitrite‐free medium and control sample suggested that nitrite plays a role in regulating the distribution of absorbed excitation energy between the two photosystems. We propose, for the first time, that the removal of loosely bound nitrite leads to migration of light‐harvesting complex II back to the PS II, and thus the mode of binding of nitrite regulates the extent of migration of antenna molecules between the two photosystems.

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On the participation of chloride in bicarbonate‐induced reversal of anion inhibition of photosystem II electron transport in spinach thylakoids

Cited by 7 publications

References 35 publications

Elucidating the site of action of oxalate in photosynthetic electron transport chain in spinach thylakoid membranes

Elucidating the site of action of oxalate in photosynthetic electron transport chain in spinach thylakoid membranes

Decay Kinetics of Tyrosine Radical (Y<sub>Z</sub><sup>*</sup>) in Chloride Anion-Depleted Photosystem 2 Studied by Time-Resolved EPR

Relation between the mode of binding of nitrite and the energy distribution between the two photosystems

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