7o1v

Structure of a Minimal Photosystem I

spinqualitylabelsall models 7o1v, resolution 4.31Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 7o1v is a 7 chain structure with sequence from Synechocystis sp. PCC 6803 substr. Kazusa. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 4.31Å Ligands: BCR, CLA, ECH, LHG, LMG, PQN, SF4, SQD Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PSAB_SYNY3 Publication Abstract from PubMed Photosystem I (PSI), found in all oxygenic photosynthetic organisms, uses solar energy to drive electron transport with nearly 100% quantum efficiency, thanks to fast energy transfer among antenna chlorophylls and charge separation in the reaction center. There is no complete consensus regarding the kinetics of the elementary steps involved in the overall trapping, especially the rate of primary charge separation. In this work, we employed two-dimensional coherent electronic spectroscopy to follow the dynamics of energy and electron transfer in a monomeric PSI complex from Synechocystis PCC 6803, containing only subunits A-E, K, and M, at 77 K. We also determined the structure of the complex to 4.3 A resolution by cryoelectron microscopy with refinements to 2.5 A. We applied structure-based modeling using a combined Redfield-Forster theory to compute the excitation dynamics. The absorptive 2D electronic spectra revealed fast excitonic/vibronic relaxation on time scales of 50-100 fs from the high-energy side of the absorption spectrum. Antenna excitations were funneled within 1 ps to a small pool of chlorophylls absorbing around 687 nm, thereafter decaying with 4-20 ps lifetimes, independently of excitation wavelength. Redfield-Forster energy transfer computations showed that the kinetics is limited by transfer from these red-shifted pigments. The rate of primary charge separation, upon direct excitation of the reaction center, was determined to be 1.2-1.5 ps(-1). This result implies activationless electron transfer in PSI. Two-Dimensional Electronic Spectroscopy of a Minimal Photosystem I Complex Reveals the Rate of Primary Charge Separation.,Akhtar P, Caspy I, Nowakowski PJ, Malavath T, Nelson N, Tan HS, Lambrev PH J Am Chem Soc. 2021 Sep 15;143(36):14601-14612. doi: 10.1021/jacs.1c05010. Epub , 2021 Sep 2. PMID:34472838 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Photosystem I 3D structures

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