Crystal structure of an integral membrane light-harvesting complex from photosynthetic bacteria

McDermott, Gerry; Prince, Stephen M.; Freer, A. A.; Hawthornthwaite-Lawless, A. M.; Papiz, Miroslav Z.; Cogdell, Richard J.; Isaacs, Neil W.

doi:10.1038/374517a0

Cited by 2,733 publications

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“…The tertiary structure of the LH2 complex from R. acidophila contains many carotenoid-Bchl interactions [3,16] and HPLC analysis has shown that during the pigment removal/ reconstitution protocols, some carotenoid loss does occur [12]. Therefore, the reduction in the overall rhodopin glucoside intensity in the absorption spectrum of the reconstituted B800-850 complex (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Bacteriochlorin‐protein interactions in native B800‐B850, B800 deficient and B800‐Bchla_p‐reconstituted complexes from Rhodopseudomonas acidophila, strain 10050

et al. 1999

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Recently, a method which allows the selective release and removal of the 800 nm absorbing bacteriochlorophyll a (B800) molecules from the LH2 complex of Rhodopseudomonas acidophila strain 10050 has been described [Fraser, N.J. (1999) Ph.D. Thesis, University of Glasgow, UK]. This procedure also allows the reconstitution of empty binding sites with the native pigment Bchla p , esterified with phytol. We have investigated the bacteriochlorophylla-protein interactions in native, B800 deficient (or B850) and in B800-bacteriochlorophylla p -reconstituted LH2 complexes by resonance Raman spectroscopy. We present the first direct structural evidence which shows that the reconstituted pigments are correctly bound within their binding pockets.z 1999 Federation of European Biochemical Societies.

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Section: Resultsmentioning

confidence: 99%

“…The determination of the crystal structure of the LH2 complex from Rhodopseudomonas acidophila 10050 to a resolution of 2.5 A î has revealed the arrangement of the pigments within that complex [3]. It has a nonameric ring structure.…”

Section: Introductionmentioning

confidence: 99%

Bacteriochlorin‐protein interactions in native B800‐B850, B800 deficient and B800‐Bchla_p‐reconstituted complexes from Rhodopseudomonas acidophila, strain 10050

et al. 1999

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“…63 Although the highest fluence used in our work is close to the threshold given above, we rule out the possibility for SSA, because we work at nM concentrations, which excludes populating the |2 LH ⟩ state by intercomplex energy transfer. From the |2 LH ⟩ state the system can decay back to the ground state or cross over within 10 ns to the triplet state | 3 B875*, 1 Car⟩ which is quenched by the carotenoids with a rate of (10 ns) −1 71 resulting in the state |3 LH ⟩ = | 1 B875, 3 Car*⟩. This state is displayed in Figure 6 as a yellow sphere with a cross that symbolizes a LH1 ring that carries a triplet state on one of the carotenoids.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

The Open, the Closed, and the Empty: Time-Resolved Fluorescence Spectroscopy and Computational Analysis of RC-LH1 Complexes from Rhodopseudomonas palustris

et al. 2015

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ABSTRACT:We studied the time-resolved fluorescence of isolated RC-LH1 complexes from Rhodopseudomonas palustris as a function of the photon fluence and the repetition rate of the excitation laser. Both parameters were varied systematically over 3 orders of magnitude. On the basis of a microstate description we developed a quantitative model for RC-LH1 and obtained very good agreement between experiments and elaborate simulations based on a global master equation approach. The model allows us to predict the relative population of RC-LH1 complexes with the special pair in the neutral state or in the oxidized state P + and those complexes that lack a reaction center. ■ INTRODUCTIONPhotosynthetic purple bacteria have evolved a wonderful modular principle for the light-harvesting (LH) apparatus that captures the solar radiation. These modules consist of pairs of hydrophobic, low molecular weight polypeptides that noncovalently bind a small number of bacteriochlorophyll (Bchl a) and carotenoid (Car) molecules and that self-assemble to produce the native pigment−protein complexes. 1−6 Most purple bacteria have two main types of complexes, the core complex, RC-LH1, and the peripheral complex, LH2. In the photosynthetic membrane the LH2 complexes are arranged in a two-dimensional network around the perimeter of the RC-LH1 complexes and the light energy absorbed by LH2 is transferred via LH1 to the reaction center (RC) where it is used to separate charge across the membrane. 7 For many years, high-resolution structural information has been available for the RC, 8−11 and the peripheral light-harvesting complexes 1−3 for a couple of species, whereas the first higher-resolution X-ray structure for a RC-LH1 complex has been determined only recently. 6 The current view is that there are at least two distinct classes of RC-LH1 complexes: Those that are monomeric, i.e., consisting of one RC surrounded by one LH1 complex, and those that are dimeric. 12,13 For RC-LH1 from Rps. palustris exists a lowresolution X-ray structure. 4 Accordingly, the RC is enclosed by an overall elliptically shaped LH1 consisting of 15 αβ-subunits that feature a gap, which is also consistent with data from optical single-molecule experiments. 14,15 Each subunit accommodates two light harvesting BChl a molecules giving rise to an absorption band at 875 nm. The reaction center complex accommodates a BChl a dimer (special pair, primary donor, P), two accessory BChl a molecules (B A , B B ), two bacteriopheophytin a (BPheo a) molecules (H A , H B ), and two ubiquinones (Q A , Q B ) bound to two protein subunits denoted L and M. The cofactors are arranged in two nearly identical branches, called A and B, which share the primary donor, P. 9,11,16,17 In particular the RC from Rhodobacter (Rb.) sphaeroides has served as a cornerstone for elucidating structure−function relationships employing a large variety of spin resonance 18−23 and optical spectroscopies. 24−31 From these studies it is well established that in the RC the absorbed photon-energy is used to dri...

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“…In the present work we will study possible C^HmO hydrogen bonding between two pigment molecules, a carotenoid rhodopin glucoside (RG) and BChl a in LH2 of the purple bacterium Rhodopseudomonas acidophila with known structure [10], by means of the characteristic features of the C^HmO hydrogen bonds: (i) geometric parameters for an ideal CĤ mONC hydrogen bond; (ii) the H-bond strength; (iii) electron density transfer from the proton-acceptor to the protondonor molecule. Finally, we will examine how the CĤ mONC hydrogen bonds a¡ect excited states of BChl a.…”

Section: Introductionmentioning

confidence: 99%

Intermolecular hydrogen bonding between carotenoid and bacteriochlorophyll in LH2

Sundström

Pullerits

2001

FEBS Letters

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We have studied van der Waals contacts of the carotenoid rhodopin glucoside (RG) with the bacteriochlorophyll pigments absorbing at 800 nm (B800) in the crystal structure of Rhodopseudomonas acidophila, and the hydrogen positions were determined from quantum chemical calculations at the HartreeF ock (6-31G) level. We have found strong evidence for hydrogen bonding between the B800 BChl and the RG from neighboring protomer units. The binding energy was estimated to be about 2 kcal/mol (700 cm 31 ). CI-singles approach and time-dependent density functional theory calculations of the B800^RG dimer indicate a red-shift (ca 2 nm) of the B800 Q y transition, along with a substantial increase of its oscillator strength, probably due to the hydrogen bonding. ß 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

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Crystal structure of an integral membrane light-harvesting complex from photosynthetic bacteria

Cited by 2,733 publications

References 20 publications

Bacteriochlorin‐protein interactions in native B800‐B850, B800 deficient and B800‐Bchla_p‐reconstituted complexes from Rhodopseudomonas acidophila, strain 10050

Bacteriochlorin‐protein interactions in native B800‐B850, B800 deficient and B800‐Bchla_p‐reconstituted complexes from Rhodopseudomonas acidophila, strain 10050

The Open, the Closed, and the Empty: Time-Resolved Fluorescence Spectroscopy and Computational Analysis of RC-LH1 Complexes from Rhodopseudomonas palustris

Intermolecular hydrogen bonding between carotenoid and bacteriochlorophyll in LH2

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Crystal structure of an integral membrane light-harvesting complex from photosynthetic bacteria

Cited by 2,733 publications

References 20 publications

Bacteriochlorin‐protein interactions in native B800‐B850, B800 deficient and B800‐Bchlap‐reconstituted complexes from Rhodopseudomonas acidophila, strain 10050

Bacteriochlorin‐protein interactions in native B800‐B850, B800 deficient and B800‐Bchlap‐reconstituted complexes from Rhodopseudomonas acidophila, strain 10050

The Open, the Closed, and the Empty: Time-Resolved Fluorescence Spectroscopy and Computational Analysis of RC-LH1 Complexes from Rhodopseudomonas palustris

Intermolecular hydrogen bonding between carotenoid and bacteriochlorophyll in LH2

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Bacteriochlorin‐protein interactions in native B800‐B850, B800 deficient and B800‐Bchla_p‐reconstituted complexes from Rhodopseudomonas acidophila, strain 10050

Bacteriochlorin‐protein interactions in native B800‐B850, B800 deficient and B800‐Bchla_p‐reconstituted complexes from Rhodopseudomonas acidophila, strain 10050