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

Semchonok, Dmitry A.; Chauvin, Jean‐Paul; Frese, Raoul N.; Jungas, Colette; Boekema, Egbert J.

doi:10.1098/rstb.2012.0063

Cited by 21 publications

(23 citation statements)

References 32 publications

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“…Semchonok et al interpreted Table 3 and Figure 5 of Crouch and Jones to signify that, for species of which both monomers and dimers exist, the ratio between them depends on the light intensity, even though the latter authors conducted no related experiment [18,14].…”

Section: Dipole Antennasmentioning

confidence: 99%

“…Some species, such as R. sphaeroides, have a polypeptide component termed "W" is found at the opening, similar to the PufX polypeptide in several Rba. species for which a precise function has long been debated [17,18,14,19,20]. The elliptical LH1 complex has an outer long axis of length 110Å and a short axis of length 95Å ; the greatest dimension of the inside of this LH1 is 78Å.…”

Section: Introductionmentioning

confidence: 99%

“…In some species, such as Rhodobaca bogoriensis, monomeric and dimeric forms have been shown to coexist [18]. The standard model to consider energy transfer within light-harvesting complexes in the photosynthesis community is the exciton theory.…”

Section: Introductionmentioning

confidence: 99%

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Proposal for verifying dipole properties of light-harvesting antennas

Ting¹

2018

Journal of Photochemistry and Photobiology B: Biology

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For light harvesters with a reaction center complex (LH1-RC complex) of three types, we propose an experiment to verify our analysis based upon antenna theories that automatically include the required structural information. Our analysis conforms to the current understanding of light-harvesting antennas in that we can explain known properties of these complexes. We provide an explanation for the functional roles of the notch at the light harvester, a functional role of the polypeptide called PufX or W at the opening, a functional role of the special pair, a reason that the cross section of the light harvester must not be circular, a reason that the light harvester must not be spherical, reasons for the use of dielectric bacteriochlorophylls instead of conductors to make the light harvester, a mechanism to prevent damage from excess sunlight, an advantage of the dimeric form, and reasons for the modular design of nature. Based upon our analysis we provide a mechanism for dimerization. We predict the dimeric form of light-harvesting complexes is favoured under intense sunlight. We further comment upon the classification of the dimeric or S-shape complexes. The S-shape complexes should not be considered as the third type of light harvester but simply as a composite form.

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Section: Dipole Antennasmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Proposal for verifying dipole properties of light-harvesting antennas

Ting¹

2018

Journal of Photochemistry and Photobiology B: Biology

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“…In Rhodobacter sphaeroides and other purple bacteria the RC-LH1 complex forms dimers, a special feature of which is its kinked conformation. The two halves of the RC-LH1 complex are inclined toward each other at an angle of 142° in R. sphaeroides [Qian et al, 2008] and 156° in R. bogoriensis [Semchonok et al, 2012]. The intrinsic curvature of the dimer leads to a local curvature of the membrane and accounts for the shape of the chromatophores, which is considered to increase the effective surface area for light gathering.…”

Section: Chromatophores and Internal Membranes Of Photosynthetic Bactmentioning

confidence: 99%

Focus on Membrane Differentiation and Membrane Domains in the Prokaryotic Cell

et al. 2013

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A summary is presented of membrane differentiation in the prokaryotic cell, with an emphasis on the organization of proteins in the plasma/cell membrane. Many species belonging to the Eubacteria and Archaea have special membrane domains and/or membrane proliferation, which are vital for different cellular processes. Typical membrane domains are found in bacteria where a specific membrane protein is abundantly expressed. Lipid rafts form another example. Despite the rareness of conventional organelles as found in eukaryotes, some bacteria are known to have an intricate internal cell membrane organization. Membrane proliferation can be divided into curvature and invaginations which can lead to internal compartmentalization. This study discusses some of the clearest examples of bacteria with such domains and internal membranes. The need for membrane specialization is highest among the heterogeneous group of bacteria which harvest light energy, such as photosynthetic bacteria and halophilic archaea. Most of the highly specialized membranes and domains, such as the purple membrane, chromatophore and chlorosome, are found in these autotrophic organisms. Otherwise the need for membrane differentiation is lower and variable, except for those structures involved in cell division. Microscopy techniques have given essential insight into bacterial membrane morphology. As microscopy will further contribute to the unraveling of membrane organization in the years to come, past and present technology in electron microscopy and light microscopy is discussed. Electron microscopy was the first to unravel bacterial morphology because it can directly visualize membranes with inserted proteins, which no other technique can do. Electron microscopy techniques developed in the 1950s and perfected in the following decades involve the thin sectioning and freeze fractioning of cells. Several studies from the golden age of these techniques show amazing examples of cell membrane morphology. More recently, light microscopy in combination with the use of fluorescent dyes has become an attractive technique for protein localization with the natural membrane. However, the resolution problem in light microscopy remains and overinterpretation of observed phenomena is a pitfall. Thus, light microscopy as a stand-alone technique is not sufficient to prove, for instance, the long-range helical distribution of proteins in membrane such as MinD spirals in Bacillus subtilis. Electron tomography is an emerging electron microscopy technique that can provide three-dimensional reconstructions of small, nonchemically fixed bacteria. It will become a useful tool for studying prokaryotic membranes in more detail and is expected to collect information complementary to those of advanced light microscopy. Together, microscopy techniques can meet the challenge of the coming years: to specify membrane structures in more detail and to bring them to the level of specific protein-protein interactions.

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“…We are interested in MP involved in the photosynthetic activity of non-sulfur purple bacteria [8]. In these, the RC-LH1-pufX complex is usually presented as a dimer [9][10][11]. The primary reactions of photosynthesis are carried out by an RC-LH1 complex formed by the photochemical reaction center (RC) and the LH1 light-harvesting pigment-protein.…”

Section: Introductionmentioning

confidence: 99%

HPTLC coupled to ESI-Tandem MS for identifying phospholipids associated to membrane proteins in photosynthetic purple bacteria

Lapieza

Jungas

Savirón

et al. 2019

Journal of Liquid Chromatography & Related Technologies

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High-performance thin-layer chromatography (HPTLC)-densitometry was directly combined with electrospray (ESI) tandem mass spectrometry for obtaining rapid and relevant structural identification of phospholipids (PL) species associated to membrane proteins (MP), in non-sulfur, purple bacteria having photosynthetic activity. Thus, species belonging to phosphatidylcholines (PC), phosphatidylethanolamines (PE), cardiolipins (CL) and phosphatidylglycerols (PG) associated to MP were investigated in bacterial membrane extracts from Rhodobacter (Rb.) blasticus, Rhodospirillum (R.) rubrum and Rhodobaca (Rbc.) bogoriensis, as well as those which are bound to a purified MPphotosynthetic complex from Rbc. bogoriensis. PL-classes were separated using a 7-step gradient-solvent sequence with a previous acid plate preconditioning, using Automated Multiple Development. Band zones of the plate corresponding to PL classes were selected to ensure their direct transfer to ion-trap MS equipment through an elution-based interface. Under the studied conditions, ESI þ-MS spectra of PC and CL mostly showed sodium adducts ([M þ Na] þ) and [M-2H þ 3Na] þ , respectively, when recorded from the plate. The respective sodium adducts were fragmented in the ion-trap, and sodium remained as the charge of the fragment ions, thus being useful for their structural identification through MS/MS. ESI-MS and MS/MS spectra of CL were also obtained as [M-2H] 2À , as well as those of PE and PG species as [M-H]and [M] À , respectively. In this way, relative composition profiles of each studied PL-class by ESI-MS, and further identification of individual PL and the molecular species belonging to each of them by MS/MS were obtained.

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

Cited by 21 publications

References 32 publications

Proposal for verifying dipole properties of light-harvesting antennas

Proposal for verifying dipole properties of light-harvesting antennas

Focus on Membrane Differentiation and Membrane Domains in the Prokaryotic Cell

HPTLC coupled to ESI-Tandem MS for identifying phospholipids associated to membrane proteins in photosynthetic purple bacteria

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