Photooxidation of cytochromes in reaction center preparations from Chromatium and Rhodopseudomonas viridis

Case, George D.; Parson, Walther; Thornber, J. Philip

doi:10.1016/0005-2728(70)90137-4

Cited by 72 publications

(25 citation statements)

References 19 publications

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“…However, in Rps. vridis, light-induced absorbance changes are observed for a pair of particulate cytochromes, but not for the cytochrome C2 (10,12).…”

Section: Discussionmentioning

confidence: 99%

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Primary structure determination of two cytochromes c2: close similarity to functionally unrelated mitochondrial cytochrome C.

Ambler¹,

Meyer²,

Kamen³

1976

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

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The amino-acid sequences of the cytochromes c2 from the photosynthetic non-sulfur purple bacteria Rhodomicrobium vannielii and-Rhiodopseudomonas viridis have been determined. Only a single residue deletion (at position 11 in horse cytochrome c) is necessary to align the sequences with those of mitochondrial cytochromes c. The overall sequence similarity between these cytochromes c2 and mitochondrial cytochromes c is closer than that between mitochondrial cytochromes c and the other cytochromes c2 of known sequence, and in the latter multiple insertions and deletions must be postulated before a match can be obtained. Nevertheless, these two cytochromes c2 show no better reactivity with the mitochondrial cytochrome c oxidase than do the less well-matched cytochromes c2. The bearing of these findings on possible evolutionary relationship between mitochondria and prokaryotes is discussed.The non-sulfur purple bacteria (Rhodospirtllaceae) are a family of photosynthetic prokaryotes (1) which possess characteristic pigments and have the same type of metabolism. They share a unique ability to utilize a wide range of simple organic carbon sources and.some members can grow nonphotosynthetically under fully aerobic conditions. However, they do not exhibit a common morphology. Rhodomicrobium vanniehi resembles the nonphotosynthetic Hyphomicrobiaceae in that daughter cells are formed as spherical buds at the ends of filaments growing out from the mother cell. Rhodopseudomonas viridis also uses a budding mode of cell division, but lacks the stalked. and branched appearance of Rhodomicrobium. All but two of the remaining Rhodospirillaceae species, including rods, spirilla, and cocci, reproduce through binary fission.All Rhodospirillaceae produce large amounts of soluble c-type cytochrome when growing photosynthetically. The best-studied example is the cytochrome C2 from Rhodospirillum rubrum (2), for which both the amino-acid sequence (3) and three-dimensional structure (4) are known. R. rubrum cytochrome C2 has a strong structural resemblance to mitochondrial cytochrome c (5) and is more closely related in sequence to the eukaryotic proteins than are any of the other bacterial cytochromes examined (6) before now.In most species of Rhodospirillaceae, the predominant ctype cytochrome resembles R. rubrum cytochrome C2 in optical spectra, in oxidation-reduction potential (7), and in limited reactivity with beef heart cytochrome oxidase (8). This is true also (B. Errede and M. D. Kamen, unpublished) for the only soluble cytochromes found in Rm. vannielil and Rps. mrldis (10). In cells of R. rubrum, the cytochrome C2 can be photooxidized (11), but in Rps. mridis light-induced absorbance changes have been ascribed (10, 12) to a pair of particulate cytochromes (analogous to those of the purple sulfur bacterium Chromatium dinosum). § From whom reprints should be requested.We have been studying the amino-acid sequences of the Rhodospirillaceae cytochromes c2 and find that they can be divided at present into at least two groups ...

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“…However, in Rps. vridis, light-induced absorbance changes are observed for a pair of particulate cytochromes, but not for the cytochrome C2 (10,12).…”

Section: Discussionmentioning

confidence: 99%

“…In cells of R. rubrum, the cytochrome C2 can be photooxidized (11), but in Rps. mridis light-induced absorbance changes have been ascribed (10,12) to a pair of particulate cytochromes (analogous to those of the purple sulfur bacterium Chromatium dinosum). § From whom reprints should be requested.…”

mentioning

confidence: 99%

Primary structure determination of two cytochromes c2: close similarity to functionally unrelated mitochondrial cytochrome C.

Ambler¹,

Meyer²,

Kamen³

1976

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

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“…9 = 350mV [2,15,16]) and the low potential Cyt c553 (Ern.9 --30mV; J-L. Under these conditions Cyt c553 is preferentially oxidized by P+ [4,16].…”

Section: Oxidation Rate Of Cytochrome C553mentioning

confidence: 99%

“…9 = 350mV [2,15,16]) and the low potential Cyt c553 (Ern.9 --30mV; J-L. Under these conditions Cyt c553 is preferentially oxidized by P+ [4,16]. The absorption changes were monitored at characteristic wavelengths for both Cyt cs53 and P. As noted above, there was some possibility of accumulation of photoreduced reaction centers, even at moderate potentials, and care was therefore taken to maintain the redox potential of the sample in the range -20 to -40 mV, somewhat above the midpoint potential of QA (Em,9 = --90 mV, J-L. Gao and C.A.…”

Section: Oxidation Rate Of Cytochrome C553mentioning

confidence: 99%

Kinetics of oxidation of the bound cytochromes in reaction centers from Rhodopseudomonas viridis

et al. 1987

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The initial oxidized species in the photochemical charge separation in reaction centers from Rps. viridis is the primary donor, P(+), a bacteriochlorophyll dimer. Bound c-type cytochromes, two high potential (Cyt c 558) and two low potential (Cyt c 553), act as secondary electron donors to P(+). Flash induced absorption changes were measured at moderate redox potential, when the high potential cytochromes were chemically reduced. A fast absorption change was due to the initial oxidation of one of the Cyt c 558 by P(+) with a rate of 3.7×10(6)s(-1) (τ=270nsec). A slower absorption change was attributable to a transfer, or sharing, of the remaining electron from one high potential heme to the other, with a rate of 2.8×10(5)s(-1) (τ=3.5 μsec). The slow change was measured at a number of wavelengths throughout the visible and near infrared and revealed that the two high potential cytochromes have slightly different differential absorption spectra, with α-band maxima at 559 nm (Cyt c 559) and 556.5 nm (Cyt c 556), and dissimilar electrochromic effects on nearby pigments. The sequence of electron transfers, following a flash, is: Cyt c 556→Cyt c 559→P(+). At lower redox potentials, a low midpoint potential cytochrome, Cyt c 553, is preferentially oxidized by P(+) with a rate of 7×10(6)s(-1) (τ=140 nsec). The assignment of the low and high potential cytochromes to the four, linearly arranged hemes of the reaction center is discussed. It is concluded that the closest heme to P must be the high potential Cyt c 559, and it is suggested that a likely arrangement for the four hemes is: c 553 c 556 c 553 c 559P.

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“…viridis and similar bacteria, it was assumed that the high-and low-potential cytochromes c are pairwise equivalent (Case et al 1970, Chamorovsky et al 1977, 1986.…”

Section: Resultsmentioning

confidence: 99%

Temperature dependence of cytochrome photooxidation and conformational dynamics of Chromatium reaction center complexes

et al. 1989

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A temperature dependence of multiheme cytochrome c oxidation induced by a laser pulse was studied in photosynthetic reaction center preparations from Chromatium minutissimum. Absorbance changes and kinetic characteristics of the reaction were measured under redox conditions where one or all of the hemes of the cytochrome subunit are chemically reduced (E h =+300 mV or E h =-20 to -60 mV respectively). In the first case photooxidation is inhibited at temperatures lower than 190-200 K with the rate constant of the photooxidation reaction being practically independent on temperature over the range of 300 to 190 K (k=2.2×10(5) s(-1)). Under reductive conditions (E h =-20 to -60 mV) lowering the temperature to 190-200 K causes the reaction to slow from k=8.3×10(5) s(-1) to 2.1×10(4) s(-1). Under further cooling down to the liquid nitrogen temperature, the reaction rate changes negligibly. The absorption amplitude decreases by 30-40% on lowering the temperature. A new physical mechanism of the observed critical effects of temperature on the rate and absorption amplitude of the multiheme cytochrome c oxidation reaction is proposed. The mechanism suggests a close interrelation between conformational mobility of the protein and elementary electron tunneling act. The effect of "freezing" conformational motion is described in terms of a local diffusion along a random rough potential.

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Photooxidation of cytochromes in reaction center preparations from Chromatium and Rhodopseudomonas viridis

Cited by 72 publications

References 19 publications

Primary structure determination of two cytochromes c2: close similarity to functionally unrelated mitochondrial cytochrome C.

Primary structure determination of two cytochromes c2: close similarity to functionally unrelated mitochondrial cytochrome C.

Kinetics of oxidation of the bound cytochromes in reaction centers from Rhodopseudomonas viridis

Temperature dependence of cytochrome photooxidation and conformational dynamics of Chromatium reaction center complexes

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