Interaction of cytochrome c with reaction centers of Rhodopseudomonas sphaeroides R-26: localization of the binding site by chemical crosslinking and immunochemical studies

Rosen, David; Okamura, M. Y.; Abresch, Edward C.; Valkirs, G E; Fehér, G.

doi:10.1021/bi00271a016

Cited by 58 publications

(50 citation statements)

References 22 publications

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“…This suggests that subunit L, the only subunit intact upon digestion, carries the binding site for cytochrome CZ. This is in agreement with the result that cytochrome cz was specifically cross-linked to subunit L [8]. Subunit M was suggested to carry the binding sites for quinones [9].…”

Section: 3 4 5supporting

confidence: 91%

Probing the smallest functional unit of the reaction center of Rhodospirillum rubrum G‐9 with proteinases

Wiemken

Bachofen

1984

FEBS Letters

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Reaction centers composed of subunits H, M, L (28 kDa, 24 kDa, 21 kDa) were isolated from Rhodospirillum rubrum G-9 and subjected to progressive digestion with proteinase K. Photoactivity and spectral characteristics were retained as long as subunit L and a characteristic fragment (about 18 kDa) of another subunit, most probably of subunit M, remained intact. This was shown by sodium dodecyl sulfate polyacrylamide gel electrophoresis and by the finding of only two amino-terminal sequences one of which was identical with that of subunit L. The rate of reduction of photooxidized P-870 was decreased in the digested preparation of the reaction center as compared with the control but the kinetics of the reduction of photooxidized cytochrome cz was unchanged. It is inferred that subunit L and a part of subunit M form the smallest functional unit of the reaction center. Reaction center subunit Digestion

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Section: 3 4 5supporting

confidence: 91%

Probing the smallest functional unit of the reaction center of Rhodospirillum rubrum G‐9 with proteinases

Wiemken

Bachofen

1984

FEBS Letters

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“…More information about these sites may be obtained by binding photoaffinity-labeled quinones to the M subunit and analyzing the peptides to which they are attached. Cytochrome c (the secondary donor) has been shown to interact with the L and M subunits (38); carboxyl groups on the L and M subunits were implicated in the binding (39). Labeling and peptide analysis of the M subunit with and without cytochrome c present may identify these groups.…”

Section: Discussionmentioning

confidence: 99%

Primary structure of the M subunit of the reaction center from Rhodopseudomonas sphaeroides

Williams

Steiner

Ogden

et al. 1983

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

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176

126

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The reaction center is a membrane-bound bacteriochlorophyll-protein complex that mediates the primary photochemical events in the photosynthetic bacterium Rhodopseudomoas sphaeroides. The previously determined amino-terminal sequences of the three subunits of the reaction center protein were used to design synthetic mixed oligonucleotide probes for the structural genes encoding the subunits. One of these probes was used to isolate and clone a fragment of DNA from R. aphaeroides that contained the gene encoding the M subunit. The nucleotide sequence of this gene was determined by the dideoxy method. In addition, a number of tryptic and chymotryptic peptides from the M protein were isolated and subjected to sequence analysis, and the sequence of the carboxyl terminus was determined. Together with the amino-terminal sequence, the data establish the primary structure of the M protein. The distribution of hydrophobic residues in the amino acid sequence suggests the presence of five membrane-spanning segments. A significant homology was found between the amino acid sequence of the M subunit and a thylakoid membrane protein (Mr 32,000) from spinach that has been implicated in herbicide and quinone binding.The reaction center (RC) is the site of the initial photochemical charge separation in the electron transfer process of photosynthesis (for reviews, see refs. 1 and 2). In the purple bacterium Rhodopseudomnas sphaeroides, the RC is part of the photosynthetic apparatus found in the highly invaginated cytoplasmic membrane that is synthesized by the bacterium under anaerobic conditions (3). The RC protein (Mr 100,000) contains three highly hydrophobic subunits, designated L, M, and H, in a 1:1:1 stoichiometry (4, 5). The cofactors found in the RC are four bacteriochlorophylls, two bacteriopheophytins, two ubiquinones, and one iron.The determination of the amino acid sequence of the RC polypeptides is essential to the detailed elucidation of the RC structure. The sequences of 25-28 amino-terminal residues of each subunit have been determined previously by automated Edman degradation (6). These were used to design mixed-sequence oligonucleotide hybridization probes for the structural genes of each of the subunits. The probe for the gene encoding the M subunit was used to identify a restriction fragment of R. sphaeroides DNA that contained the gene. The nucleotide sequence of this gene was determined by the dideoxy method and is presented together with the amino acid sequence derived from it. The sequences of the carboxyl terminus and of several peptides were determined for corroboration of the sequence obtained from the DNA. Preliminary accounts of this work have been given (7,8).EXPERIMENTAL PROCEDURES Materials. Large fragment Escherichia coli DNA polymerase I, M13mp7 replicative form (RF) DNA, M13 24-base-pair primer fragment, dideoxynucleotides, and the restriction enzymes Acc I, BamHI, EcoRI, HindIII, Hpa II, Kpn I, Sal I, Sma I, and Taq I were obtained from Bethesda Research Laboratories. T4 polynucleotide k...

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“…~ 1994 International Union of Crystallography Printed in Great Britain -all rights reserved of the RC transfers an electron to the photo-oxidized bacteriochlorophyll dimer (D ~) (Prince, Cogdell & Crofts, 1974;Prince, Baccarini-Melandri, Hauska, Melandri & Crofts, 1975;Overfield, Wraight & Devault, 1979;Rosen, Okamura & Feher, 1980;Rosen, Okamura, Abresch, Valkris & Feher, 1983). The oxidized ferricytochrome c2 is re-reduced by cytochrome bc~ to regenerate ferrocytochrome c2 (reviewed in Crofts & Wraight, 1983).…”

Section: Introductionmentioning

confidence: 99%

Crystallization and X-ray structure determination of cytochrome c2 from Rhodobacter sphaeroides in three crystal forms

Axelrod¹,

Fehér²,

Allen³

et al. 1994

Acta Cryst D

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Cytochrome c2 serves as the secondary electron donor that reduces the photo-oxidized bacteriochlorophyll dimer in photosynthetic bacteria. Cytochrome c2 from Rhodobacter sphaeroides has been crystallized in three different forms. At high ionic strength, crystals of a hexagonal space group (P6~22) were obtained, while at low ionic strength, triclinic (P1) and tetragonal (P4~2~2) crystals were formed. The three-dimensional structures of the cytochrome in all three crystal forms have been determined by X-ray diffraction at resolutions of 2.20 ~ (hexagonal), 1.95 A, (triclinic) and 1.53 A (tetragonal). The most significant difference observed was the binding of an imidazole molecule to the iron atom of the heme group in the hexagonal structure. This binding displaces the sulfur atom of Met l00, which forms the axial ligand in the triclinic and tetragonal structures.

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Interaction of cytochrome c with reaction centers of Rhodopseudomonas sphaeroides R-26: localization of the binding site by chemical crosslinking and immunochemical studies

Cited by 58 publications

References 22 publications

Probing the smallest functional unit of the reaction center of Rhodospirillum rubrum G‐9 with proteinases

Probing the smallest functional unit of the reaction center of Rhodospirillum rubrum G‐9 with proteinases

Primary structure of the M subunit of the reaction center from Rhodopseudomonas sphaeroides

Crystallization and X-ray structure determination of cytochrome c2 from Rhodobacter sphaeroides in three crystal forms

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