Structural basis for energy transduction by respiratory alternative complex III

• Published in: Nature communications Vol. 9; no. 1; pp. 1728 - 10
• Main Authors: Sousa, Joana S., Calisto, Filipa, Langer, Julian D., Mills, Deryck J., Refojo, Patrícia N., Teixeira, Miguel, Kühlbrandt, Werner, Vonck, Janet, Pereira, Manuela M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.04.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 101/28; 631/45/535/1258/1259; 631/57/1464; 631/92/607/1168; Amino Acid Sequence; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Binding Sites; Catalysis; Cofactors; Cryoelectron Microscopy; Cytochrome; Cytochrome c; Electrochemical potential; Electrochemistry; Electron microscopy; Electron transfer; Electron Transport - genetics; Electron Transport Complex III - chemistry; Electron Transport Complex III - genetics; Electron Transport Complex III - metabolism; Energy transduction; Gene Expression; Heme - chemistry; Heme - metabolism; Humanities and Social Sciences; Hydroquinone; Hydroquinones - chemistry; Hydroquinones - metabolism; Iron; Kinetics; Mitochondria; Models, Molecular; multidisciplinary; Oxidation-Reduction; Oxidoreductase; Prokaryotes; Protein Binding; Protein Conformation, alpha-Helical; Protein Conformation, beta-Strand; Protein Interaction Domains and Motifs; Protein Multimerization; Protein Subunits - chemistry; Protein Subunits - genetics; Protein Subunits - metabolism; Protons; Rhodothermus - enzymology; Rhodothermus - genetics; Science; Science (multidisciplinary); Sulfur; Thermodynamics
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-04141-8

Electron transfer in respiratory chains generates the electrochemical potential that serves as energy source for the cell. Prokaryotes can use a wide range of electron donors and acceptors and may have alternative complexes performing the same catalytic reactions as the mitochondrial complexes. This is the case for the alternative complex III (ACIII), a quinol:cytochrome c /HiPIP oxidoreductase. In order to understand the catalytic mechanism of this respiratory enzyme, we determined the structure of ACIII from Rhodothermus marinus at 3.9 Å resolution by single-particle cryo-electron microscopy. ACIII presents a so-far unique structure, for which we establish the arrangement of the cofactors (four iron–sulfur clusters and six c -type hemes) and propose the location of the quinol-binding site and the presence of two putative proton pathways in the membrane. Altogether, this structure provides insights into a mechanism for energy transduction and introduces ACIII as a redox-driven proton pump. Some prokaryotes use alternative respiratory chain complexes, such as the alternative complex III (ACIII), to generate energy. Here authors provide the cryoEM structure of ACIII from Rhodothermus marinus which shows the arrangement of cofactors and provides insights into the mechanism for energy transduction.