3lw5 | pdb_00003lw5
Improved model of plant photosystem I
Structural highlights
Function[CB23_PEA] The light-harvesting complex (LHC) functions as a light receptor, it captures and delivers excitation energy to photosystems with which it is closely associated.[1] May channel protons produced in the catalytic Mn center of water oxidation into the thylakoid lumen.[2] [PSAB_PEA] 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-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 (By similarity). [PSAA_PEA] 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-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. [CB24_PEA] The light-harvesting complex (LHC) functions as a light receptor, it captures and delivers excitation energy to photosystems with which it is closely associated.[3] May channel protons produced in the catalytic Mn center of water oxidation into the thylakoid lumen.[4] [PSAC_PEA] Apoprotein for the two 4Fe-4S centers FA and FB of photosystem I (PSI); essential for photochemical activity. FB is the terminal electron acceptor of PSI, donating electrons to ferredoxin. The C-terminus interacts with PsaA/B/D and helps assemble the protein into the PSI complex. Required for binding of PsaD and PsaE to PSI. PSI is a plastocyanin-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 (By similarity).[HAMAP-Rule:MF_01303] [PSAI_PEA] May help in the organization of the PsaL subunit. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedPhotosystem I functions as a sunlight energy converter, catalyzing one of the initial steps in driving oxygenic photosynthesis in cyanobacteria, algae, and higher plants. Functionally, Photosystem I captures sunlight and transfers the excitation energy through an intricate and precisely organized antenna system, consisting of a pigment network, to the center of the molecule, where it is used in the transmembrane electron transfer reaction. Our current understanding of the sophisticated mechanisms underlying these processes has profited greatly from elucidation of the crystal structures of the Photosystem I complex. In this report, we describe the developments that ultimately led to enhanced structural information of plant Photosystem I. In addition, we report an improved crystallographic model at 3.3-A resolution, which allows analysis of the structure in more detail. An improved electron density map yielded identification and tracing of subunit PsaK. The location of an additional ten beta-carotenes as well as five chlorophylls and several loop regions, which were previously uninterpretable, are now modeled. This represents the most complete plant Photosystem I structure obtained thus far, revealing the locations of and interactions among 17 protein subunits and 193 non-covalently bound photochemical cofactors. Using the new crystal structure, we examine the network of contacts among the protein subunits from the structural perspective, which provide the basis for elucidating the functional organization of the complex. Structure determination and improved model of plant photosystem I.,Amunts A, Toporik H, Borovikova A, Nelson N J Biol Chem. 2010 Jan 29;285(5):3478-86. Epub 2009 Nov 18. PMID:19923216[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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