6et5
Reaction centre light harvesting complex 1 from Blc. virids
Structural highlights
FunctionCYCR_BLAVI The reaction center of purple bacteria contains a tightly bound cytochrome molecule which re-reduces the photo oxidized primary electron donor.[1] Publication Abstract from PubMedThe light-harvesting 1-reaction centre (LH1-RC) complex is a key functional component of bacterial photosynthesis. Here we present a 2.9 A resolution cryo-electron microscopy structure of the bacteriochlorophyll b-based LH1-RC complex from Blastochloris viridis that reveals the structural basis for absorption of infrared light and the molecular mechanism of quinone migration across the LH1 complex. The triple-ring LH1 complex comprises a circular array of 17 beta-polypeptides sandwiched between 17 alpha- and 16 gamma-polypeptides. Tight packing of the gamma-apoproteins between beta-polypeptides collectively interlocks and stabilizes the LH1 structure; this, together with the short Mg-Mg distances of bacteriochlorophyll b pairs, contributes to the large redshift of bacteriochlorophyll b absorption. The 'missing' 17th gamma-polypeptide creates a pore in the LH1 ring, and an adjacent binding pocket provides a folding template for a quinone, Q P, which adopts a compact, export-ready conformation before passage through the pore and eventual diffusion to the cytochrome bc 1 complex. Cryo-EM structure of the Blastochloris viridis LH1-RC complex at 2.9 A.,Qian P, Siebert CA, Wang P, Canniffe DP, Hunter CN Nature. 2018 Apr;556(7700):203-208. doi: 10.1038/s41586-018-0014-5. Epub 2018 Apr, 4. PMID:29618818[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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