Supramolecular organization of photosynthetic complexes in membranes of Roseiflexus castenholzii

Majumder, Erica L.-W.; Olsen, John D.; Qian, Pu; Collins, Aaron M.; Hunter, C. Neil; Blankenship, Robert E.

doi:10.1007/s11120-015-0179-9

Cited by 14 publications

(7 citation statements)

References 63 publications

(86 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…BChl pigments have been omitted for clarity. The EM models were shrunk 10% to reduce or eliminate the effects caused by detergent and stain on their size [46] , [47] , [48] . …”

Section: Resultsmentioning

confidence: 99%

The C-terminus of PufX plays a key role in dimerisation and assembly of the reaction center light-harvesting 1 complex from Rhodobacter sphaeroides

Qian

Martin

et al. 2017

Biochimica et Biophysica Acta (BBA) - Bioenergetics

Self Cite

View full text Add to dashboard Cite

In bacterial photosynthesis reaction center-light-harvesting 1 (RC-LH1) complexes trap absorbed solar energy by generating a charge separated state. Subsequent electron and proton transfers form a quinol, destined to diffuse to the cytochrome bc1 complex. In bacteria such as Rhodobacter (Rba.) sphaeroides and Rba. capsulatus the PufX polypeptide creates a channel for quinone/quinol traffic across the LH1 complex that surrounds the RC, and it is therefore essential for photosynthetic growth. PufX also plays a key role in dimerization of the RC-LH1-PufX core complex, and the structure of the Rba. sphaeroides complex shows that the PufX C-terminus, particularly the region from X49-X53, likely mediates association of core monomers. To investigate this putative interaction we analysed mutations PufX R49L, PufX R53L, PufX R49/53L and PufX G52L by measuring photosynthetic growth, fractionation of detergent-solubilised membranes, formation of 2-D crystals and electron microscopy. We show that these mutations do not affect assembly of PufX within the core or photosynthetic growth but they do prevent dimerization, consistent with predictions from the RC-LH1-PufX structure. We obtained low resolution structures of monomeric core complexes with and without PufX, using electron microscopy of negatively stained single particles and 3D reconstruction; the monomeric complex with PufX corresponds to one half of the dimer structure whereas LH1 completely encloses the RC if the gene encoding PufX is deleted. On the basis of the insights gained from these mutagenesis and structural analyses we propose a sequence for assembly of the dimeric RC-LH1-PufX complex.

show abstract

“…BChl pigments have been omitted for clarity. The EM models were shrunk 10% to reduce or eliminate the effects caused by detergent and stain on their size [46] , [47] , [48] . …”

Section: Resultsmentioning

confidence: 99%

The C-terminus of PufX plays a key role in dimerisation and assembly of the reaction center light-harvesting 1 complex from Rhodobacter sphaeroides

Qian

Martin

et al. 2017

Biochimica et Biophysica Acta (BBA) - Bioenergetics

Self Cite

View full text Add to dashboard Cite

show abstract

“…The photosynthetic bacterium R. castenholzii has evolved a simple but efficient cyclic ETC to transform solar energy into chemical energy that is different from the linear respiratory chain ( 31 – 33 ). Our study has revealed the structure of the first photosynthetic ACIII comprising six conserved subunits, in both the air-oxidized and dithionite-reduced states, as well as the nature and position of the cofactors, including six hemes and four iron-sulfur clusters.…”

Section: Discussionmentioning

confidence: 99%

Cryo-EM structures of the air-oxidized and dithionite-reduced photosynthetic alternative complex III from Roseiflexus castenholzii

et al. 2020

Self Cite

View full text Add to dashboard Cite

Alternative complex III (ACIII) is a multisubunit quinol:electron acceptor oxidoreductase that couples quinol oxidation with transmembrane proton translocation in both the respiratory and photosynthetic electron transport chains of bacteria. The coupling mechanism, however, is poorly understood. Here, we report the cryo-EM structures of air-oxidized and dithionite-reduced ACIII from the photosynthetic bacterium Roseiflexus castenholzii at 3.3- and 3.5-Å resolution, respectively. We identified a menaquinol binding pocket and an electron transfer wire comprising six hemes and four iron-sulfur clusters that is capable of transferring electrons to periplasmic acceptors. We detected a proton translocation passage in which three strictly conserved, mid-passage residues are likely essential for coupling the redox-driven proton translocation across the membrane. These results allow us to propose a previously unrecognized coupling mechanism that links the respiratory and photosynthetic functions of ACIII. This study provides a structural basis for further investigation of the energy transformation mechanisms in bacterial photosynthesis and respiration.

show abstract

“…The reduced hydroquinone then diffuses from its binding site to the membrane pool through a gap in the LH ring. The hydroquinone is further oxidized by a novel alternative complex (ACIII) found in FAPs that functionally replaces the Cyt bc 1 complex of purple bacteria 33 , and the electron released during this redox reaction is further transferred to a blue copper protein called auracyanin and finally transferred back to the RC via four hemes bound in the Cyt c subunit at the periplasmic side (Fig. 4c ).…”

Section: Discussionmentioning

confidence: 99%

“…Negative stain electron microscopy revealed the core complex from R. castenholzii has a similar size and shape with that of purple bacteria 11 , 13 , 15 , 32 , and has 15 ± 1 LHαβ subunits assembled into a slightly elliptical LH ring, surrounding a tetra-heme cytochrome c bound to the RC 26 . Recently, an electron microscopic 3D reconstruction of the core complex with a resolution of 14.6 Å showed that the LH antenna embraces the RC to form a complete elliptical ring, with the cytochrome subunit protruding to the periplasmic space 33 . However, due to the limited resolution, molecular details about the subunit arrangement and pigment organization are still elusive.…”

Section: Introductionmentioning

confidence: 99%

Cryo-EM structure of the RC-LH core complex from an early branching photosynthetic prokaryote

Xin¹,

Shi²,

Niu³

et al. 2018

Nat Commun

Self Cite

View full text Add to dashboard Cite

Photosynthetic prokaryotes evolved diverse light-harvesting (LH) antennas to absorb sunlight and transfer energy to reaction centers (RC). The filamentous anoxygenic phototrophs (FAPs) are important early branching photosynthetic bacteria in understanding the origin and evolution of photosynthesis. How their photosynthetic machinery assembles for efficient energy transfer is yet to be elucidated. Here, we report the 4.1 Å structure of photosynthetic core complex from Roseiflexus castenholzii by cryo-electron microscopy. The RC–LH complex has a tetra-heme cytochrome c bound RC encompassed by an elliptical LH ring that is assembled from 15 LHαβ subunits. An N-terminal transmembrane helix of cytochrome c inserts into the LH ring, not only yielding a tightly bound cytochrome c for rapid electron transfer, but also opening a slit in the LH ring, which is further flanked by a transmembrane helix from a newly discovered subunit X. These structural features suggest an unusual quinone exchange model of prokaryotic photosynthetic machinery.

show abstract

Supramolecular organization of photosynthetic complexes in membranes of Roseiflexus castenholzii

Cited by 14 publications

References 63 publications

The C-terminus of PufX plays a key role in dimerisation and assembly of the reaction center light-harvesting 1 complex from Rhodobacter sphaeroides

The C-terminus of PufX plays a key role in dimerisation and assembly of the reaction center light-harvesting 1 complex from Rhodobacter sphaeroides

Cryo-EM structures of the air-oxidized and dithionite-reduced photosynthetic alternative complex III from Roseiflexus castenholzii

Cryo-EM structure of the RC-LH core complex from an early branching photosynthetic prokaryote

Contact Info

Product

Resources

About