Isolation and properties of PS II membrane fragments depleted of the non heme iron center

Kurreck, Jens; Garbers, Axel; Reifarth, F.; Andréasson, Lars-Erik; Parak, F.; Ренгер, Г.

doi:10.1016/0014-5793(96)00061-0

Cited by 19 publications

(21 citation statements)

References 34 publications

(41 reference statements)

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“…Differences in quadrupole splittings indicate two different environments of the iron atoms. The component characterized by a quadrupole splitting of about 1 mm/s can be ascribed to cytochrome b 559 [19,[24][25][26] and that one characterized by a quadrupole splitting of about 0.55 mm/s to the non-heme iron [19]. The more detailed description of these data is given in [19].…”

Section: Resultsmentioning

confidence: 99%

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b₅₅₉in a Chlamydomonas reinhardtii PSI Minus Mutant

et al. 2006

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Mössbauer spectroscopy was applied, for the first time, to study the interaction of copper ions with the non-heme iron and the heme iron of cytochrome b559 in photosystem II thylakoids isolated from a Chlamydomonas reinhardtii photosystem I minus mutant. We showed that copper ions oxidize the heme iron and change its low spin state into a high spin state. This is probably due to deprotonation of the histidine coordinating the heme. We also found that copper preserves the non-heme iron in a low spin ferrous state, enhancing the covalence of iron bonds as compared to the untreated sample. We suggest that a disruption of hydrogen bonds stabilizing the quinone-iron complex by Cu 2+ is the mechanism responsible for a new arrangement of the binding site of the non-heme iron leading to its more "tense" structure. Such a diamagnetic state of the non-heme iron induced by copper results in a magnetic decoupling of iron from the primary quinone acceptor. These results indicate that Cu does not cause removal of the non--heme iron from its binding site. The observed Cu 2+ action on the non--heme iron and cytochrome b 559 is similar to that previously observed for α-tocopherol quinone.

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Section: Resultsmentioning

confidence: 99%

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b₅₅₉in a Chlamydomonas reinhardtii PSI Minus Mutant

et al. 2006

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“…This means that both of them are in the reduced form Fe 2+ and further that only the Fe 2+ low spin state may be assigned to both components ( δ 1 ≈ δ 2 ≈0.480±0.005 mm/s and Δ E 1 =1.05±0.05 mm/s; Δ E 2 =0.55±0.03 mm/s at 80 K). There is no doubt that the component characterized by a quadrupole splitting of about 1 mm/s can be ascribed to cytochrome b 559 [25,35,44]. The isomer shift and quadrupole splitting are characteristic for low spin Fe 2+ heme iron in a strong ligand field [45].…”

Section: Resultsmentioning

confidence: 99%

Mössbauer studies of the non‐heme iron and cytochrome b₅₅₉ in a Chlamydomonas reinhardtii PSI⁻ mutant and their interactions with α‐tocopherol quinone

et al. 2003

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Mo « ssbauer studies of the non-heme iron and cytochrome b 559 in a Chlamydomonas reinhardtii PSI Abstract Spin and valence states of the non-heme iron and the heme iron of cytochrome b 559 , as well as their interactions with K K-tocopherol quinone (K K-TQ) in photosystem II (PSII) thylakoid membranes prepared from the Chlamydomonas reinhardtii PSI 3 mutant have been studied using Mo «ssbauer spectroscopy. Both of the iron atoms are in low spin ferrous states. The Debye temperature of the non-heme is 194 K and of the heme iron is 182 K. The treatment of K K-TQ does not change the spin and the valence states of the non-heme iron but enhances the covalence of its bonds. K K-TQ oxidizes the heme iron into the high spin Fe 3+ state. A possible role of the non-heme iron and K K-TQ in electron £ow through the PSII is discussed.

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“…Extraction of the Fe from PSII inhibits forward ET from Q A Ϫ and alters its H-bonding properties (44), and for BRCs, diminished yield of Q A Ϫ formation and lower yields and rates of interquinone ET were observed (45,46). However, when the Fe was substituted by other, e.g.…”

Section: Discussionmentioning

confidence: 99%

Carboxylate Shifts Steer Interquinone Electron Transfer in Photosynthesis

Chernev

Zaharieva

Dau

et al. 2011

Journal of Biological Chemistry

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Understanding the mechanisms of electron transfer (ET) in photosynthetic reaction centers (RCs) may inspire novel catalysts for sunlight-driven fuel production. The electron exit pathway of type II RCs comprises two quinone molecules working in series and in between a non-heme iron atom with a carboxyl ligand (bicarbonate in photosystem II (PSII), glutamate in bacterial RCs). For decades, the functional role of the iron has remained enigmatic. We tracked the iron site using microsecond-resolution x-ray absorption spectroscopy after laser-flash excitation of PSII. After formation of the reduced primary quinone, Q A ؊ , the x-ray spectral changes revealed a transition (t1 ⁄ 2 ≈ 150 s) from a bidentate to a monodentate coordination of the bicarbonate at the Fe(II) (carboxylate shift), which reverted concomitantly with the slower ET to the secondary quinone Q B . A redox change of the iron during the ET was excluded. Density-functional theory calculations corroborated the carboxylate shift both in PSII and bacterial RCs and disclosed underlying changes in electronic configuration. We propose that the iron-carboxyl complex facilitates the first interquinone ET by optimizing charge distribution and hydrogen bonding within the Q A FeQ B triad for high yield Q B reduction. Formation of a specific priming intermediate by nuclear rearrangements, setting the stage for subsequent ET, may be a common motif in reactions of biological redox cofactors.

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Isolation and properties of PS II membrane fragments depleted of the non heme iron center

Cited by 19 publications

References 34 publications

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b₅₅₉in a Chlamydomonas reinhardtii PSI Minus Mutant

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b₅₅₉in a Chlamydomonas reinhardtii PSI Minus Mutant

Mössbauer studies of the non‐heme iron and cytochrome b₅₅₉ in a Chlamydomonas reinhardtii PSI⁻ mutant and their interactions with α‐tocopherol quinone

Carboxylate Shifts Steer Interquinone Electron Transfer in Photosynthesis

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Isolation and properties of PS II membrane fragments depleted of the non heme iron center

Cited by 19 publications

References 34 publications

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b559in a Chlamydomonas reinhardtii PSI Minus Mutant

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b559in a Chlamydomonas reinhardtii PSI Minus Mutant

Mössbauer studies of the non‐heme iron and cytochrome b559 in a Chlamydomonas reinhardtii PSI− mutant and their interactions with α‐tocopherol quinone

Carboxylate Shifts Steer Interquinone Electron Transfer in Photosynthesis

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Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b₅₅₉in a Chlamydomonas reinhardtii PSI Minus Mutant

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b₅₅₉in a Chlamydomonas reinhardtii PSI Minus Mutant

Mössbauer studies of the non‐heme iron and cytochrome b₅₅₉ in a Chlamydomonas reinhardtii PSI⁻ mutant and their interactions with α‐tocopherol quinone