Mössbauer spectroscopy studies of photosynthetic reaction centers from Rhodopseudomonas sphaeroides R-26

Boso, Brian; Debrunner, Peter G.; Okamura, M. Y.; Fehér, G.

doi:10.1016/0005-2728(81)90200-0

Cited by 48 publications

(18 citation statements)

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“…rubrum RCs exists predominantly in a low spin ferrous state. It is believed that NHFe should exist solely in a high spin ferrous state [18,31] in photosynthetic RCs although this diamagnetic state of NHFe has been already observed in mutated BBY PSII isolated from algae [16,17] and a similar Mössbauer spectrum of Rs. rubrum chromatophores with only a small contribution of the high spin NHFe was detected [9].…”

Section: Resultsmentioning

confidence: 99%

“…Finally, the spectrum obtained for the control sample of chromatophores contains a third component with IS = 0.97 ± 0.02 mm/s and QS = 2.53 ± 0.14 mm/s, typical hyperfine parameters for the high spin Fe 2+ state. This component is usually ascribed to NHFe, which high spin ferrous state in photosynthetic RC of type Q is well known [10,18]. In order to improve the fit of the spectrum collected for control RCs one can also add a minor contribution of this high spin ferrous state but IS in this case is shifted to 1.18 ± 0.10 mm/s.…”

Section: Resultsmentioning

confidence: 99%

“…In this paper we show that NHFe in RC isolated from Rhodospirillum (Rs.) rubrum occurs almost exclusively in a low spin state, while in RC from Rhodobacter sphaeroides it was observed in a high spin state [7,18]. At the same time, the rate of ET in the former RC is slower [19].…”

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confidence: 99%

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Influence of Cd²⁺on the spin state of non-heme iron and on protein local motions in reactions centers from purple photosynthetic bacteriumRhodospirilium rubrum

Lipińska

Orzechowska

Fiedor

et al. 2010

J. Phys.: Conf. Ser.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Influence of Cd²⁺on the spin state of non-heme iron and on protein local motions in reactions centers from purple photosynthetic bacteriumRhodospirilium rubrum

Lipińska

Orzechowska

Fiedor

et al. 2010

J. Phys.: Conf. Ser.

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“…These include magnetic susceptibility measurements (45), Mossbauer spectroscopy (46), extended x-ray fine structure absorption (47,48), and EPR (49,50). The conclusions about the Fe2+ arrived at from these experiments are (i) it is in a high spin Fe2+ state irrespective of the oxidation state of the quinone acceptors (45,46); (ii) it does not form a direct ligand to the quinones (45)(46)(47)(48)(49); (iii) it interacts magnetically with the unpaired electron on the quinone (45,49,50); (iv) its most likely number of ligands is six, with an average bond length of 2.12 ± 0.03 A (47,48); (v) its environment is a distorted octahedron (45)(46)(47)(48)(49); (vi) it is closer to QB than to QA (49). It was originally thought that the Fe2+ may play an important role in the electron transfer from QA and QB (6,51).…”

Section: Resultsmentioning

confidence: 99%

Structure of the reaction center from Rhodobacter sphaeroides R-26: the cofactors.

Allen

Fehér²,

Yeates³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

908

608

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The three-dimensional structure of the cofactors of the reaction center of Rhodobacter sphaeroides R-26 has been determined by x-ray diffraction and refined at a resolution of 2.8 A with an R value of 26%. The main features of the structure are similar to the ones determined for Rhodopseudomonas viridis [Michel, H., Epp, 0. & Deisenhofer, J. (1986) EMBO J. 5, 2445EMBO J. 5, -2451. The cofactors are arranged along two branches, which are approximately related to each other by a 2-fold symmetry axis. The structure is well suited to produce light-induced charge separation across the membrane. Most of the structural features predicted from physical and biochemical measurements are confirmed by the x-ray structure.The reaction center (RC) is an integral membrane proteinpigment complex that mediates the primary processes of photosynthesis-i.e., the light-induced electron transfers from a donor to a series of acceptor species. The three-dimensional structure of the RC from the photosynthetic bacterium Rhodopseudomonas viridis has recently been determined by x-ray diffraction at a resolution of 2.9 A (1-3). In this paper, we report the structure analysis of the RC from another purple bacterium, the carotenoidless mutant R-26 of Rhodobacter sphaeroides (previously called Rhodopseudomonas sphaeroides). The motivation for undertaking the structure determination of the RC of a second bacterial species was 2-fold. (i) The RC from Rb. sphaeroides has been investigated for the past two decades and, consequently, is the best characterized RC (for reviews see refs. 4 and 5); in addition, the methodologies for manipulating its structure (e.g., exchanging cofactors, dissociating and reassociating the subunits) have been worked out in detail (4-10). (ii) The availability of structures from two organisms may help in elucidating structure-function relationships by correlating differences in structure with differences in function.The RC from Rb. sphaeroides is composed of three protein subunits-L, M, and H-and the following cofactors: four bacteriochlorophylls (Bchls), two bacteriopheophytins (Bphes), two ubiquinones, and one nonheme iron. The RC from R. viridis has an additional subunit, a cytochrome with four c-type hemes; its Bchls and Bphes are of the "b" type instead of the "a" type found in Rb. sphaeroides, and its primary quinone is a menaquinone. Notwithstanding these differences, the two structures were found to be very similar. This made it possible to use the method of molecular replacement (11) to solve the phase problem in the x-ray analysis (12)(13)(14). The crystals of Rb. sphaeroides diffract at least to a resolution of 2.6 A and retain the ability to perform the primary photochemistry (15). We have solved the structure of the protein and the cofactors to a resolution of 2.8 A with an R factor of 26%. In this paper, we report the structure of the cofactors. The structure of the protein, the relation of the RC protein to the membrane, and the interaction of the cofactors with the protein will be reported in ...

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“…ET from the primary quinone Q A to the secondary quinone QB occurs in the presence of a nearby Fe ion [6][7][8][9][10][11]. Steady-state Mössbauer experiments [11,12] on unreduced RCs have shown that the oxidation state of Fe is +2 with a high-spin electronic ground state (S = 2). It is also known [13] that the valency of the Fe-ion is not changed during the ET reaction.…”

Section: Introductionmentioning

confidence: 99%

A Model of spin catalysis in bacterial photosynthetic reaction centres

1999

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A model of influence of non-heme Fe 21 ion on kinetics of electron transfer between quinone anion-radicals Qp and QB in bacterial reaction centres is proposed and investigated. Physical mechanism of the influence is associated with singlet-triplet transitions in QAQB pair caused by interactions with paramagnetic Fe z . The model incorporates exchange couplings between the particles and zero-field splittings in high-spin Fe 2 '. These interactions are shown to catalyze electron transfer in triplet pairs and alter the reaction yield significantly.

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Mössbauer spectroscopy studies of photosynthetic reaction centers from Rhodopseudomonas sphaeroides R-26

Cited by 48 publications

References 13 publications

Influence of Cd²⁺on the spin state of non-heme iron and on protein local motions in reactions centers from purple photosynthetic bacteriumRhodospirilium rubrum

Influence of Cd²⁺on the spin state of non-heme iron and on protein local motions in reactions centers from purple photosynthetic bacteriumRhodospirilium rubrum

Structure of the reaction center from Rhodobacter sphaeroides R-26: the cofactors.

A Model of spin catalysis in bacterial photosynthetic reaction centres

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Mössbauer spectroscopy studies of photosynthetic reaction centers from Rhodopseudomonas sphaeroides R-26

Cited by 48 publications

References 13 publications

Influence of Cd2+on the spin state of non-heme iron and on protein local motions in reactions centers from purple photosynthetic bacteriumRhodospirilium rubrum

Influence of Cd2+on the spin state of non-heme iron and on protein local motions in reactions centers from purple photosynthetic bacteriumRhodospirilium rubrum

Structure of the reaction center from Rhodobacter sphaeroides R-26: the cofactors.

A Model of spin catalysis in bacterial photosynthetic reaction centres

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Influence of Cd²⁺on the spin state of non-heme iron and on protein local motions in reactions centers from purple photosynthetic bacteriumRhodospirilium rubrum

Influence of Cd²⁺on the spin state of non-heme iron and on protein local motions in reactions centers from purple photosynthetic bacteriumRhodospirilium rubrum