7m78
Room Temperature XFEL Crystallography reveals asymmetry in the vicinity of the two phylloquinones in Photosystem I
Structural highlights
FunctionPSAA_THEVB PsaA and PsaB bind P700, the primary electron donor of photosystem I (PSI), as well as the electron acceptors A0, A1 and FX. PSI is a plastocyanin/cytochrome c6-ferredoxin oxidoreductase, converting photonic excitation into a charge separation, which transfers an electron from the donor P700 chlorophyll pair to the spectroscopically characterized acceptors A0, A1, FX, FA and FB in turn. Oxidized P700 is reduced on the lumenal side of the thylakoid membrane by plastocyanin or cytochrome c6.[1] [2] [3] [4] Publication Abstract from PubMedPhotosystem I (PS I) has a symmetric structure with two highly similar branches of pigments at the center that are involved in electron transfer, but shows very different efficiency along the two branches. We have determined the structure of cyanobacterial PS I at room temperature (RT) using femtosecond X-ray pulses from an X-ray free electron laser (XFEL) that shows a clear expansion of the entire protein complex in the direction of the membrane plane, when compared to previous cryogenic structures. This trend was observed by complementary datasets taken at multiple XFEL beamlines. In the RT structure of PS I, we also observe conformational differences between the two branches in the reaction center around the secondary electron acceptors A(1A) and A(1B). The pi-stacked Phe residues are rotated with a more parallel orientation in the A-branch and an almost perpendicular confirmation in the B-branch, and the symmetry breaking PsaB-Trp673 is tilted and further away from A(1A). These changes increase the asymmetry between the branches and may provide insights into the preferential directionality of electron transfer. Room temperature XFEL crystallography reveals asymmetry in the vicinity of the two phylloquinones in photosystem I.,Keable SM, Kolsch A, Simon PS, Dasgupta M, Chatterjee R, Subramanian SK, Hussein R, Ibrahim M, Kim IS, Bogacz I, Makita H, Pham CC, Fuller FD, Gul S, Paley D, Lassalle L, Sutherlin KD, Bhowmick A, Moriarty NW, Young ID, Blaschke JP, de Lichtenberg C, Chernev P, Cheah MH, Park S, Park G, Kim J, Lee SJ, Park J, Tono K, Owada S, Hunter MS, Batyuk A, Oggenfuss R, Sander M, Zerdane S, Ozerov D, Nass K, Lemke H, Mankowsky R, Brewster AS, Messinger J, Sauter NK, Yachandra VK, Yano J, Zouni A, Kern J Sci Rep. 2021 Nov 8;11(1):21787. doi: 10.1038/s41598-021-00236-3. PMID:34750381[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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