Structures of
            <i>Rhodopseudomonas palustris</i>
            RC-LH1 complexes with open or closed quinone channels

Swainsbury, David J. K.; Qian, Pu; Jackson, Philip J.; Faries, Kaitlyn M.; Niedzwiedzki, Dariusz M.; Martin, Elizabeth C.; Farmer, David A.; Malone, Lorna A.; Thompson, Rebecca; Ranson, Neil A.; Canniffe, Daniel P.; Dickman, Mark J.; Holten, Dewey; Kirmaier, Christine; Hitchcock, Andrew; Hunter, C. Neil

doi:10.1126/sciadv.abe2631

Cited by 53 publications

(84 citation statements)

References 64 publications

(90 reference statements)

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“…S4). Similar channels have also been observed in other LH1 complexes with closed ring-like structures 3, 6, 12 , suggesting that these hydrophobic channels function as paths for quinone transport into and out of the complex. Such a function is supported by molecular dynamics simulation 13 and biochemical analysis 14 .…”

Section: Figsupporting

confidence: 76%

Cryo-EM Structure of the Photosynthetic LH1-RC Complex from Rhodospirillum rubrum

Tani

Kanno

et al. 2021

Preprint

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We present a cryo-EM structure of the light-harvesting-reaction center (LH1-RC) core complex from purple phototrophic bacterium Rhodospirillum (Rsp.) rubrum at 2.76 Å resolution. The LH1 complex forms a closed, slightly elliptical ring structure with 16 αβ-polypeptides surrounding the RC. Our biochemical analysis detected rhodoquinone (RQ) molecules in the purified LH1-RC, and the cryo-EM density map specifically positions RQ at the QA site in the RC. The geranylgeraniol sidechains of bacteriochlorophyll (BChl) aG coordinated by LH1 β-polypeptides exhibit a highly homologous tail-up conformation that allows for interactions with the bacteriochlorin rings of nearby LH1 α-associated BChls aG. The structure also revealed key protein–protein interactions in both N- and C-terminal regions of the LH1 αβ-polypeptides, mainly within a face-to-face structural subunit. Our findings enable to evaluate past experimental and computational results obtained with this widely used organism and provide crucial information for more detailed exploration of light-energy conversion, quinone transport, and structure—function relationships in pigment-protein complexes.

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Section: Figsupporting

confidence: 76%

Cryo-EM Structure of the Photosynthetic LH1-RC Complex from Rhodospirillum rubrum

Tani

Kanno

et al. 2021

Preprint

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“…tepidum ( 6 , 7 ) and likely in the LH1 ring of Rps. palustris ( 12 ). Computational simulations on a modeled LH1 structure also suggested the possibility that ubiquinone can diffuse through the closed LH1 ring ( 35 ).…”

Section: Resultsmentioning

confidence: 99%

“…2H and table S5). The periplasmic end of the carotenoid is in close proximity to the N-terminal domain of PufX (Lys 12 S5).…”

Section: Interactions Between Pufx and Rc-lh1mentioning

confidence: 99%

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Cryo-EM structure of the photosynthetic RC-LH1-PufX supercomplex at 2.8-Å resolution

et al. 2021

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The reaction center (RC)−light-harvesting complex 1 (LH1) supercomplex plays a pivotal role in bacterial photosynthesis. Many RC-LH1 complexes integrate an additional protein PufX that is key for bacterial growth and photosynthetic competence. Here, we present a cryo–electron microscopy structure of the RC-LH1-PufX supercomplex from Rhodobacter veldkampii at 2.8-Å resolution. The RC-LH1-PufX monomer contains an LH ring of 15 αβ-polypeptides with a 30-Å gap formed by PufX. PufX acts as a molecular “cross brace” to reinforce the RC-LH1 structure. The unusual PufX-mediated large opening in the LH1 ring and defined arrangement of proteins and cofactors provide the molecular basis for the assembly of a robust RC-LH1-PufX supercomplex and efficient quinone transport and electron transfer. These architectural features represent the natural strategies for anoxygenic photosynthesis and environmental adaptation.

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“…4). This corresponds to a ratio of approximately two carotenoids per αβ-polypeptides in contrast to the one carotenoid per αβpair commonly found in other LH1 complexes 26,27,31,32 . All methoxy groups of the Rba.…”

mentioning

confidence: 74%

A Novel Membrane Protein in the Rhodobacter sphaeroides LH1-RC Photocomplex

Tani

Kvp

Kanno

et al. 2021

Preprint

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We present a cryo-EM structure of the monomeric light-harvesting-reaction center (LH1-RC) core complex from photosynthetic purple bacterium Rhodobacter (Rba.) sphaeroides at 2.9 Å resolution. The LH1 complex forms a C-shaped structure composed of 14 αβ-polypeptides around the RC with a large ring opening. From the cryo-EM density map, a previously unrecognized integral membrane protein, referred to as protein-U, was identified. Protein-U has a U-shaped conformation near the LH1-ring opening and was annotated as a hypothetical protein in the Rba. sphaeroides genome. Deletion of protein-U resulted in a mutant strain that expressed a much-reduced amount of the dimeric LH1-RC, indicating an important role for protein-U in dimerization of the LH1-RC complex. PufX was located opposite protein-U on the LH1-ring opening, and both its position and conformation differed from that of previous reports of dimeric LH1-RC structures obtained at low-resolution. Twenty-six molecules of the carotenoid spheroidene arranged in two distinct configurations were resolved in the Rba. sphaeroides LH1 and were positioned within the complex to block its pores. Our findings offer a new view of the core photocomplex of Rba. sphaeroides and the connections between structure and function in bacterial photocomplexes in general.

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Structures of Rhodopseudomonas palustris RC-LH1 complexes with open or closed quinone channels

Cited by 53 publications

References 64 publications

Cryo-EM Structure of the Photosynthetic LH1-RC Complex from Rhodospirillum rubrum

Cryo-EM Structure of the Photosynthetic LH1-RC Complex from Rhodospirillum rubrum

Cryo-EM structure of the photosynthetic RC-LH1-PufX supercomplex at 2.8-Å resolution

A Novel Membrane Protein in the Rhodobacter sphaeroides LH1-RC Photocomplex

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