Native architecture of the photosynthetic membrane from Rhodobacter veldkampii

Liu, Luning; Sturgis, James N.; Scheuring, Simon

doi:10.1016/j.jsb.2010.08.010

Cited by 36 publications

(30 citation statements)

References 62 publications

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“…The dimentions of the PSII supercomplexes and their supramolecular organization are extensively characterized by EM (5,7,8,(25)(26)(27)(28); however, in recent years atomic force microscopy (AFM) became the technique of choice for probing the lateral protein arrangement in photosynthetic membranes because of its high resolution and the possibility to measure in fluid (i.e., closer to the in vivo environment). AFM helped building remarkable molecular models of the organization of the photosynthetic apparatus in photosynthetic bacteria (29)(30)(31)(32), red algae (33), and higher plants (34)(35)(36)(37).…”

Section: Introductionmentioning

confidence: 99%

Low pH Modulates the Macroorganization and Thermal Stability of PSII Supercomplexes in Grana Membranes

Stoichev

Krumova

Andreeva

et al. 2015

Biophysical Journal

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Protonation of the lumen-exposed residues of some photosynthetic complexes in the grana membranes occurs under conditions of high light intensity and triggers a major photoprotection mechanism known as energy dependent nonphotochemical quenching. We have studied the role of protonation in the structural reorganization and thermal stability of isolated grana membranes. The macroorganization of granal membrane fragments in protonated and partly deprotonated state has been mapped by means of atomic force microscopy. The protonation of the photosynthetic complexes has been found to induce large-scale structural remodeling of grana membranes-formation of extensive domains of the major light-harvesting complex of photosystem II and clustering of trimmed photosystem II supercomplexes, thinning of the membrane, and reduction of its size. These events are accompanied by pronounced thermal destabilization of the photosynthetic complexes, as evidenced by circular dichroism spectroscopy and differential scanning calorimetry. Our data reveal a detailed nanoscopic picture of the initial steps of nonphotochemical quenching.

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Section: Introductionmentioning

confidence: 99%

Low pH Modulates the Macroorganization and Thermal Stability of PSII Supercomplexes in Grana Membranes

Stoichev

Krumova

Andreeva

et al. 2015

Biophysical Journal

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“…palustris [3], Phaeospirillum molischianum [4], Rhodobacter (Rba.) veldkampii [5,6], Rps. rubrum [7], Rba.…”

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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“…Most elegantly the two applications were combined allowing the attribution of structural changes to force events (8). More recently, the AFM has proven the unique tool for studying the supramolecular assembly of the bacterial photosynthetic unit (9)(10)(11)(12) and has provided a solid basis for the understanding of the ensemble function of the photosynthetic proteins (4,(13)(14)(15).…”

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confidence: 99%

“…The LH2 structure is well described by X-ray crystallography (16,17) and AFM in native membranes (12,(18)(19)(20). Typically, the LH2 complexes appear as circular oligomers of nine αβ subunits, including 18 long-wavelength-absorbing bacteriochlorophyll (BChl) molecules sandwiched between the inner ring of α-polypeptides and the outer ring of β-polypeptides.…”

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confidence: 99%

Forces guiding assembly of light-harvesting complex 2 in native membranes

Liu

Duquesne

Oesterhelt

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Interaction forces of membrane protein subunits are of importance in their structure, assembly, membrane insertion, and function. In biological membranes, and in the photosynthetic apparatus as a paradigm, membrane proteins fulfill their function by ensemble actions integrating a tight assembly of several proteins. In the bacterial photosynthetic apparatus light-harvesting complexes 2 (LH2) transfer light energy to neighboring tightly associated core complexes, constituted of light-harvesting complexes 1 (LH1) and reaction centers (RC). While the architecture of the photosynthetic unit has been described, the forces and energies assuring the structural and functional integrity of LH2, the assembly of LH2 complexes, and how LH2 interact with the other proteins in the supramolecular architecture are still unknown. Here we investigate the molecular forces of the bacterial LH2 within the native photosynthetic membrane using atomic force microscopy single-molecule imaging and force measurement in combination. The binding between LH2 subunits is fairly weak, of the order of k B T , indicating the importance of LH2 ring architecture. In contrast LH2 subunits are solid with a free energy difference of 90 k B T between folded and unfolded states. Subunit α-helices unfold either in one-step, α-and β-polypeptides unfold together, or sequentially. The unfolding force of transmembrane helices is approximately 150 pN. In the two-step unfolding process, the β-polypeptide is stabilized by the molecular environment in the membrane. Hence, intermolecular forces influence the structural and functional integrity of LH2.atomic force microscopy | photosynthesis | protein unfolding | membrane protein assembly M embrane protein function is intimately linked and influenced by its structural integrity and molecular environment (1-3). Photosynthesis is a paradigm of such orchestrated molecular action, for which the implicated proteins have evolved to form supramolecular assemblies (4). Knowledge of supramolecular architecture and interaction forces and energies are indispensable for a complete understanding of a membrane protein structure and function.The atomic force microscope (AFM) (5) can be used as a high-resolution imaging (6) and as a force-measurement tool (7). Most elegantly the two applications were combined allowing the attribution of structural changes to force events (8). More recently, the AFM has proven the unique tool for studying the supramolecular assembly of the bacterial photosynthetic unit (9-12) and has provided a solid basis for the understanding of the ensemble function of the photosynthetic proteins (4, 13-15).The light-harvesting process in photosynthetic bacteria starts with photon capture at the peripheral light-harvesting complex 2 (LH2) that transfers the absorbed excitation energy to the light-harvesting complex 1 (LH1) associated with the reaction center (RC). The LH2 structure is well described by X-ray crystallography (16, 17) and AFM in native membranes (12,(18)(19)(20). Typically, the LH2 complexes appe...

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Native architecture of the photosynthetic membrane from Rhodobacter veldkampii

Cited by 36 publications

References 62 publications

Low pH Modulates the Macroorganization and Thermal Stability of PSII Supercomplexes in Grana Membranes

Low pH Modulates the Macroorganization and Thermal Stability of PSII Supercomplexes in Grana Membranes

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

Forces guiding assembly of light-harvesting complex 2 in native membranes

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