6hum | pdb_00006hum
Structure of the photosynthetic complex I from Thermosynechococcus elongatus
Structural highlights
FunctionNU1C_THEVB NDH-1 shuttles electrons from an unknown electron donor, via FMN and iron-sulfur (Fe-S) centers, to quinones in the respiratory and/or the photosynthetic chain. The immediate electron acceptor for the enzyme in this species is believed to be plastoquinone. Couples the redox reaction to proton translocation, and thus conserves the redox energy in a proton gradient.[HAMAP-Rule:MF_01350] Publication Abstract from PubMedPhotosynthetic complex I enables cyclic electron flow around photosystem I, a regulatory mechanism for photosynthetic energy conversion. We report a 3.3-A resolution cryo-EM structure of photosynthetic complex I from the cyanobacterium Thermosynechococcus elongatus. The model reveals structural adaptations that facilitate binding and electron transfer from the photosynthetic electron carrier ferredoxin. By mimicking cyclic electron flow with isolated components in vitro, we demonstrate that ferredoxin directly mediates electron transfer between photosystem I and complex I, instead of using intermediates such as NADPH. A large rate constant for association of ferredoxin to complex I indicates efficient recognition, with the protein subunit NdhS being the key component in this process. Structural adaptations of photosynthetic complex I enable ferredoxin-dependent electron transfer.,Schuller JM, Birrell JA, Tanaka H, Konuma T, Wulfhorst H, Cox N, Schuller SK, Thiemann J, Lubitz W, Setif P, Ikegami T, Engel BD, Kurisu G, Nowaczyk MM Science. 2018 Dec 20. pii: science.aau3613. doi: 10.1126/science.aau3613. PMID:30573545[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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