7ZDI

PucB-LH2 complex from Rps. palustris

Summary for 7ZDI

• Entry DOI: 10.2210/pdb7zdi/pdb
• EMDB information: 14650
• Descriptor: Light-harvesting protein, PucA-LH2-gamma, BACTERIOCHLOROPHYLL A, ... (5 entities in total)
• Functional Keywords: light harvesting complex 2, lh2, rps. palustris, photosynthesis, purple bacteria, cryo-em, single particle analysis
• Biological source: Rhodopseudomonas palustris; More
• Total number of polymer chains: 19
• Total formula weight: 159425.79

Authors

Qian, P.,Cogdell, R.J.,Nguyen-Phan, T.C. (deposition date: 2022-03-29, release date: 2022-10-05, Last modification date: 2024-11-13)

Primary citation

Qian, P.,Nguyen-Phan, C.T.,Gardiner, A.T.,Croll, T.I.,Roszak, A.W.,Southall, J.,Jackson, P.J.,Vasilev, C.,Castro-Hartmann, P.,Sader, K.,Hunter, C.N.,Cogdell, R.J.
Cryo-EM structures of light-harvesting 2 complexes from Rhodopseudomonas palustris reveal the molecular origin of absorption tuning.
Proc.Natl.Acad.Sci.USA, 119:e2210109119-e2210109119, 2022

PubMed Abstract: The genomes of some purple photosynthetic bacteria contain a multigene family encoding a series of α- and β-polypeptides that together form a heterogeneous antenna of light-harvesting 2 (LH2) complexes. To unravel this complexity, we generated four sets of deletion mutants in , each encoding a single type of gene pair and enabling the purification of complexes designated as PucA-LH2, PucB-LH2, PucD-LH2, and PucE-LH2. The structures of all four purified LH2 complexes were determined by cryogenic electron microscopy (cryo-EM) at resolutions ranging from 2.7 to 3.6 Å. Uniquely, each of these complexes contains a hitherto unknown polypeptide, γ, that forms an extended undulating ribbon that lies in the plane of the membrane and that encloses six of the nine LH2 αβ-subunits. The γ-subunit, which is located near to the cytoplasmic side of the complex, breaks the C9 symmetry of the LH2 complex and binds six extra bacteriochlorophylls (BChls) that enhance the 800-nm absorption of each complex. The structures show that all four complexes have two complete rings of BChls, conferring absorption bands centered at 800 and 850 nm on the PucA-LH2, PucB-LH2, and PucE-LH2 complexes, but, unusually, the PucD-LH2 antenna has only a single strong near-infared (NIR) absorption peak at 803 nm. Comparison of the cryo-EM structures of these LH2 complexes reveals altered patterns of hydrogen bonds between LH2 αβ-side chains and the bacteriochlorin rings, further emphasizing the major role that H bonds play in spectral tuning of bacterial antenna complexes.

PubMed: 36251992
DOI: 10.1073/pnas.2210109119

Experimental method

ELECTRON MICROSCOPY (2.9 Å)