Dataset Information

High-resolution cryo-EM structure of the respiratory alternative complex III from Rhodothermus marinus

ABSTRACT: Electron transfer in respiratory chains generates the electrochemical potential that serves as the energy source for ATP synthesis, solute transport and motility. In eukaryotes and many bacteria, the respiratory chain consists of four electron transport complexes, known as complex I to IV. Respiratory chains of some prokaryotes differ in composition and organization. They can use a wide range of electron donors and acceptors and may have complexes performing the same catalytic reaction. The diversity and apparent redundancy of prokaryotic respiratory chains reflects the versatility and robustness of the organisms. Many of these alternative respiratory chain complexes are either unknown or their structures and mechanisms remain elusive. In this work we describe a 3.9 A cryo-EM structure of the alternative complex III (ACIII) from Rhodothermus marinus, which we demonstrated takes over the role of canonical respiratory complex III (bc1 complex), even though it is structurally unrelated. Our structure reveals that ACIII is an integral membrane protein complex of at least 7 subunits (ActABCDEFH). The periplasmic domain, with ActA, B, E and H, harbours four iron-sulphur clusters and six C-type hemes. The cofactors form two electron wires that converge on the putative quinol-binding site in subunit ActC. The two homologous subunits, ActC and ActF, each have two four-helix bundles in the membrane, with several conserved polar residues that delineate putative proton channels. ACIII meets all requirements for an energy-transducing machine that couples electron transfer from quinol to the oxygen reductase, to translocation of protons across the membrane.

INSTRUMENT(S): impact II

ORGANISM(S): Rhodothermus Marinus

TISSUE(S): Prokaryotic Cell

SUBMITTER: Julian Langer

LAB HEAD: Julian David Langer

PROVIDER: PXD008247 | Pride | 2018-05-08

REPOSITORIES: Pride

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Publications

Structural basis for energy transduction by respiratory alternative complex III.

Sousa Joana S JS Calisto Filipa F Langer Julian D JD Mills Deryck J DJ Refojo Patrícia N PN Teixeira Miguel M Kühlbrandt Werner W Vonck Janet J Pereira Manuela M MM

Nature communications 20180430 1

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 ...[more]

PMID: 29712914

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Project description:Abstract: The crenarchaeal order Sulfolobales collectively contains at least five major terminal oxidase complexes. Based on genome sequence information, all five complexes are found only in Metallosphaera sedula and Sulfolobus tokodaii, the two sequenced Sulfolobales capable of iron oxidization. While specific respiratory complexes in certain Sulfolobales have been characterized previously as proton pumps for maintaining intracellular pH and generating proton motive force (pmf), their contribution to sulfur and iron biooxidation has not been considered. For M. sedula growing in the presence of ferrous iron and reduced inorganic sulfur compounds (RISCs), global transcriptional analysis was used to track the response of specific genes associated with these complexes, as well as other known and putative respiratory electron transport chain elements. ORFs from all five terminal oxidase or bc1-like complexes were stimulated on one or more conditions tested. Components of the fox (Msed0467-0489) and soxNL-cbsABA (Msed0500-0505) terminal/quinol oxidase clusters were triggered by ferrous iron, while the soxABCDD' terminal oxidase cluster (Msed0285-0291) were induced by tetrathionate and S°. Chemolithotrophic electron transport elements, including a putative tetrathionate hydrolase (Msed0804), a novel polysulfide/sulfur/DMSO reductase-like complex (Msed0812-0818), and a novel heterodisulfide reductase-like complex (Msed1542-1550), were also stimulated by RISCs. Furthermore, several hypothetical proteins were found to have strong responses to ferrous iron or RISCs, suggesting additional candidates in iron or sulfur oxidation-related pathways. From this analysis, a comprehensive model for electron transport in M. sedula could be proposed as the basis for examining specific details of iron and sulfur oxidation in this bioleaching archaeon. 5-slide loop of Mse cells includes 5 conditions tested: yeast exact (Y), yeast extract + ferrous sulfate (YFS), yeast extract + potassium sulfate (YKS), yeast extract + potassium tetrathionate (YKT), and yeast extract + elemental sulfur (YS). Half of an RNA sample for one condition was labeled with Cy3 while the other half was labeled with Cy5. The two differently labeled samples were run on different slides. Each probe is spotted on each slide 5 times (5 replicates; spot intensities for all replicates on slide provided in associated raw data file).

Dataset Information

High-resolution cryo-EM structure of the respiratory alternative complex III from Rhodothermus marinus

Publications

Structural basis for energy transduction by respiratory alternative complex III.

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