8x2j

Cryo-EM structure of the photosynthetic alternative complex III with a quinone inhibitor HQNO from Chloroflexus aurantiacus

spinqualitylabelsall models 8x2j, resolution 2.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 8x2j is a 8 chain structure with sequence from Chloroflexus aurantiacus J-10-fl. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 2.7Å Ligands: HEC, HQO, JL3, JLQ, JM9 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A9WEV2_CHLAA Publication Abstract from PubMed Alternative complex III (ACIII) couples quinol oxidation and electron acceptor reduction with potential transmembrane proton translocation. It is compositionally and structurally different from the cytochrome bc1/b6f complexes but functionally replaces these enzymes in the photosynthetic and/or respiratory electron transport chains (ETCs) of many bacteria. However, the true compositions and architectures of ACIIIs remain unclear, as do their structural and functional relevance in mediating the ETCs. We here determined cryogenic electron microscopy structures of photosynthetic ACIII isolated from Chloroflexus aurantiacus (CaACIIIp), in apo-form and in complexed form bound to a menadiol analog 2-heptyl-4-hydroxyquinoline-N-oxide. Besides 6 canonical subunits (ActABCDEF), the structures revealed conformations of 2 previously unresolved subunits, ActG and I, which contributed to the complex stability. We also elucidated the structural basis of menaquinol oxidation and subsequent electron transfer along the [3Fe-4S]-6 hemes wire to its periplasmic electron acceptors, using electron paramagnetic resonance, spectroelectrochemistry, enzymatic analyses, and molecular dynamics simulations. A unique insertion loop in ActE was shown to function in determining the binding specificity of CaACIIIp for downstream electron acceptors. This study broadens our understanding of the structural diversity and molecular evolution of ACIIIs, enabling further investigation of the (mena)quinol oxidoreductases-evolved coupling mechanism in bacterial energy conservation. Cryo-EM structure of HQNO-bound alternative complex III from the anoxygenic phototrophic bacterium Chloroflexus aurantiacus.,Xin J, Min Z, Yu L, Yuan X, Liu A, Wu W, Zhang X, He H, Wu J, Xin Y, Blankenship RE, Tian C, Xu X Plant Cell. 2024 Oct 3;36(10):4212-4233. doi: 10.1093/plcell/koae029. PMID:38299372 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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