The solution structure of the PufX polypeptide from <i>Rhodobacter sphaeroides</i>

Tunnicliffe, Richard B.; Ratcliffe, Emma C.; Hunter, C. Neil; Williamson, Michael P.

doi:10.1016/j.febslet.2006.11.065

Cited by 36 publications

(44 citation statements)

References 35 publications

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“…veldkampii PufX sequence compared to those of other Rhodobacter species (WxxxQMxxGA). The cluster QMxxGA in all other Rhodobacter species PufX is exposed to the same a-helix surface of about 36 Å 2 area in the solution NMR structure of PufX (Tunnicliffe et al, 2006;Wang et al, 2007) (Fig. 6B and C).…”

Section: The Pufx Polypeptidementioning

confidence: 91%

Native architecture of the photosynthetic membrane from Rhodobacter veldkampii

Liu

Sturgis

Scheuring

2011

Journal of Structural Biology

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Section: The Pufx Polypeptidementioning

confidence: 91%

Native architecture of the photosynthetic membrane from Rhodobacter veldkampii

Liu

Sturgis

Scheuring

2011

Journal of Structural Biology

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“…7,24 Although the bend and the N-terminal loop for PufX both closely follow 2NRG ( Figure S6B), they were determined completely independently of the NMR structures. 7,24 Furthermore, the position of PufX next to LH1α1 has also been determined independently by cryo-EM (3), although the PufX transmembrane domain is now established as 17 Å from the original best estimate of its position in the EM projection map. 3 Figure 2C shows the position of PufX and RC-H in relation to the RC Q B inferred from the RC structure (PDB 1PCR) incorporated into our dimer model.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Three-Dimensional Structure of the Rhodobacter sphaeroides RC-LH1-PufX Complex: Dimerization and Quinone Channels Promoted by PufX

et al. 2013

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Reaction center-light harvesting 1 (RC-LH1) complexes are the fundamental units of bacterial photosynthesis, which use solar energy to power the reduction of quinone to quinol prior to the formation of the proton gradient that drives ATP synthesis. The dimeric RC-LH1-PufX complex of Rhodobacter sphaeroides is composed of 64 polypeptides and 128 cofactors, including 56 LH1 bacteriochlorophyll a (BChl a) molecules that surround and donate energy to the two RCs. The 3D structure was determined to 8 Å by X-ray crystallography, and a model was built with constraints provided by electron microscopy (EM), nuclear magnetic resonance (NMR), mass spectrometry (MS), and site-directed mutagenesis. Each half of the dimer complex consists of a RC surrounded by an array of 14 LH1 αβ subunits, with two BChls sandwiched between each αβ pair of transmembrane helices. The N- and C-terminal extrinsic domains of PufX promote dimerization by interacting with the corresponding domains of an LH1 β polypeptide from the other half of the RC-LH1-PufX complex. Close contacts between PufX, an LH1 αβ subunit, and the cytoplasmic domain of the RC-H subunit prevent the LH1 complex from encircling the RC and create a channel connecting the RC QB site to an opening in the LH1 ring, allowing Q/QH₂ exchange with the external quinone pool. We also identified a channel that connects the two halves of the dimer, potentially forming a long-range pathway for quinone migration along rows of RC-LH1-PufX complexes in the membrane. The structure of the RC-LH1-PufX complex explains the crucial role played by PufX in dimer formation, and it shows how quinone traffic traverses the LH1 complex as it shuttles between the RC and the cytochrome bc₁ complex.

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“…The construction is summarized here. The model was built using solution structures of LH1β, and PufX (38, 39), the three-dimensional structure of the RC (40, 41), and homology modeling of LH1α based on the solution structure of LH1α of Rhodospirillum rubrum (42). The proteins were then assembled in an arrangement proposed by an 8.5 Å-resolution cryo-EM projection map (23).…”

Section: Methodsmentioning

confidence: 99%