6NIN

Rhodobacter sphaeroides bc1 with STIGMATELLIN A

Summary for 6NIN

• Entry DOI: 10.2210/pdb6nin/pdb
• Related: 2QJK 2QJY
• Descriptor: Cytochrome b, FE2/S2 (INORGANIC) CLUSTER, Cytochrome c1, ... (10 entities in total)
• Functional Keywords: mitochondrial respiratory chain complex, cytochrome bc1, inhibitors, electron transfer, oxidoreductase, oxidoreductase-inhibitor complex, oxidoreductase/inhibitor
• Biological source: Rhodobacter sphaeroides (strain ATCC 17023 / 2.4.1 / NCIB 8253 / DSM 158); More
• Total number of polymer chains: 18
• Total formula weight: 616428.78

Authors

Xia, D.,Zhou, F.,Esser, L. (deposition date: 2018-12-31, release date: 2019-06-19, Last modification date: 2024-10-23)

Primary citation

Esser, L.,Zhou, F.,Yu, C.A.,Xia, D.
Crystal structure of bacterial cytochromebc1in complex with azoxystrobin reveals a conformational switch of the Rieske iron-sulfur protein subunit.
J.Biol.Chem., 294:12007-12019, 2019

PubMed Abstract: Cytochrome complexes (cyt ), also known as complex III in mitochondria, are components of the cellular respiratory chain and of the photosynthetic apparatus of non-oxygenic photosynthetic bacteria. They catalyze electron transfer (ET) from ubiquinol to cytochrome and concomitantly translocate protons across the membrane, contributing to the cross-membrane potential essential for a myriad of cellular activities. This ET-coupled proton translocation reaction requires a gating mechanism that ensures bifurcated electron flow. Here, we report the observation of the Rieske iron-sulfur protein (ISP) in a mobile state, as revealed by the crystal structure of cyt from the photosynthetic bacterium in complex with the fungicide azoxystrobin. Unlike cyt inhibitors stigmatellin and famoxadone that immobilize the ISP, azoxystrobin causes the ISP-ED to separate from the cyt subunit and to remain in a mobile state. Analysis of anomalous scattering signals from the iron-sulfur cluster of the ISP suggests the existence of a trajectory for electron delivery. This work supports and solidifies the hypothesis that the bimodal conformation switch of the ISP provides a gating mechanism for bifurcated ET, which is essential to the Q-cycle mechanism of cyt function.

PubMed: 31182483
DOI: 10.1074/jbc.RA119.008381

Experimental method

X-RAY DIFFRACTION (3.6 Å)