7dgz
Activity optimized complex I (closed form)
Structural highlights
FunctionNU2M_BOVIN Core subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (Complex I) that is believed to belong to the minimal assembly required for catalysis. Complex I functions in the transfer of electrons from NADH to the respiratory chain. The immediate electron acceptor for the enzyme is believed to be ubiquinone. Publication Abstract from PubMedAims: Mitochondrial respiratory supercomplexes mediate redox electron transfer, generating a proton gradient for ATP synthesis. To provide structural information on the function of supercomplexes in physiologically relevant conditions, we conducted cryoelectron microscopy studies with supercomplexes in a lipid-preserving state. Results: Here, we present cryoelectron microscopy structures of bovine respiratory supercomplex I(1)III(2)IV(1) by using a lipid-preserving sample preparation. The preparation greatly enhances the intercomplex quinone transfer activity. The structures reveal large intercomplex motions that result in different shapes and sizes of the intercomplex space between complexes I and III, forming a dynamic substrate pool. Biochemical and structural analyses indicated that intercomplex phospholipids mediate the intercomplex motions. An analysis of the different classes of focus-refined complex I showed that structural switches due to quinone reduction led to the formation of a novel channel that could transfer reduced quinones to the intercomplex substrate pool. Innovation and Conclusion: Our results indicate potential mechanism for the facilitated electron transfer involving a dynamic substrate pool and intercomplex movement by which supercomplexes play an active role in the regulation of metabolic flux and reactive oxygen species. A Dynamic Substrate Pool Revealed by cryo-EM of a Lipid-Preserved Respiratory Supercomplex.,Jeon TJ, Lee SG, Yoo SH, Kim M, Song D, Ryu J, Park H, Kim DS, Hyun J, Kim HM, Ryu SE Antioxid Redox Signal. 2022 Apr 27. doi: 10.1089/ars.2021.0114. PMID:34913730[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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