Crystal Structure of the RC-LH1 Core Complex from
            <i>Rhodopseudomonas palustris</i>

Roszak, A.W.; Howard, Tina D.; Southall, June; Gardiner, Alastair T.; Law, Christopher J.; Isaacs, Neil W.; Cogdell, Richard J.

doi:10.1126/science.1088892

Cited by 625 publications

(563 citation statements)

References 27 publications

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“…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.…”

Section: ■ Introductionsupporting

confidence: 84%

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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Section: ■ Introductionsupporting

confidence: 84%

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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“…There are no highresolution data of a dimeric RC-LH1 complex, but a 4.8 Å -resolution structure is available for the monomeric RC-LH1 from Rps. palustris [3]. The RC-LH1 structure shows the RC surrounded by an oval LH1 complex, which consists of 15 pairs of transmembrane helical a and b-apoproteins and their coordinated bacteriochlorophylls.…”

Section: Introductionmentioning

confidence: 99%

“…viridis [2], Rhodopseudomonas (Rps.) palustris [3], Phaeospirillum molischianum [4], Rhodobacter (Rba.) veldkampii [5,6], Rps.…”

Section: Introductionmentioning

confidence: 99%

Structure of the dimeric RC–LH1–PufX complex from Rhodobaca bogoriensis investigated by electron microscopy

Semchonok

Chauvin

Frese

et al. 2012

Phil. Trans. R. Soc. B

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Electron microscopy and single-particle averaging were performed on isolated reaction centre (RC)-antenna complexes (RC-LH1-PufX complexes) of Rhodobaca bogoriensis strain LBB1, with the aim of establishing the LH1 antenna conformation, and, in particular, the structural role of the PufX protein.Projection maps of dimeric complexes were obtained at 13 Å resolution and show the positions of the 2 Â 14 LH1 a-and b-subunits. This new dimeric complex displays two open, C-shaped LH1 aggregates of 13 ab polypeptides partially surrounding the RCs plus two LH1 units forming the dimer interface in the centre. Between the interface and the two half rings are two openings on each side. Next to the openings, there are four additional densities present per dimer, considered to be occupied by four copies of PufX. The position of the RC in our model was verified by comparison with RC-LH1-PufX complexes in membranes. Our model differs from previously proposed configurations for Rhodobacter species in which the LH1 ribbon is continuous in the shape of an S, and the stoichiometry is of one PufX per RC.

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“…The complex LH1, which surrounds the reaction center (RC), is composed of B880, a bacteriochlorophyll dimer with an absorption maximum at 880 nm. These structures ostensibly exhibit formation as a ring when studied independently, though some studies have suggested that the ring is not closed when the RC is present [21,26]. The LH1 complex is in turn surrounded by a number of LH2 complexes, comprising both B850 rings above and B800 rings below.…”

Section: Light-harvesting Complexesmentioning

confidence: 99%

“…In order to most effectively utilize the sunlight that falls on them, all photosynthetic organisms have a system of antenna complexes surrounding the reaction centers where photosynthesis takes place. The photosystems of purple bacteria, such as Rhodopseudomonas acidophila and Rhodobacter sphaeroides [19], have been most extensively studied [20][21][22] by means of ultrashort pulsed laser spectroscopy [23], X-ray protein crystallography [24], as well as hole-burning and absorption studies [25]. In such systems bacteriochlorophyll is the key light-harvesting pigment.…”

Section: Light-harvesting Complexesmentioning

confidence: 99%