The Archaeal Respiratory Supercomplex SoxM from S.acidocaldarius Combines Features of Quinole and Cytochrome c Oxidases
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L. Komorowski
Abstract
The hyperthermoacidophilic archaeon Sulfolobus acidocaldarius has a unique respiratory system with at least two terminal oxidases. Genetic and preliminary biochemical studies suggested the existence of a unique respiratory supercomplex, SoxM. Here we show (i) that all respective genes are translated into polypeptides, and (ii) that the supercomplex can be separated from the alternative oxidase SoxABCD and in that way characterized in a catalytically competent form for the first time. It acts as a quinol oxidase and contains a total of seven metal redox centers. One of it the blue copper protein sulfocyanin functionally links two subcomplexes. One is a bb3-type terminal oxidase moiety containing CuA and CuB, whereas the other consists of a Rieske FeSprotein and a homolog to cytochrome b in this case hosting two hemes AS. Based on a 1:1 stoichiometry, 1 mol complex contains 6 mol Fe and 4 mol Cu. Its activity is completely inhibited by cyanide and strongly by aurachinC and D derivatives as inhibitors of the quinol binding site. These data suggest that the complex provides two proton pumping sites. Interestingly, subunitII reveals an unusual pH dependence and is proposed to act as a pH sensor as well as a regulator of catalytic activity via a reversible transition between two states of the CuA ligation. This is a novel hint at how S. acidocaldarius can adapt to and survive in its extreme natural environment.
Copyright © 2002 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- Pigment Epithelium-Derived Factor (PEDF), a Serpin with Potent Anti-Angiogenic and Neurite Outgrowth-promoting Properties
- Mechanism of Inhibition of RNA Polymerase I Transcription by DNA-dependent Protein Kinase
- Evidence for Haploinsufficiency of the Human HNF1α Gene Revealed by Functional Characterization of MODY3-Associated Mutations
- In vitro and in vivo Stability of the 2ζ2 Protein Complex of the Broad Host-Range Streptococcus pyogenes pSM19035 Addiction System
- Effects of Antineoplastic Agents on Cytoplasmic and Membrane-Bound Heat Shock Protein 70 (Hsp70) Levels
- Characterization of the VPS10 Domain of SorLA/LR11 as Binding Site for the Neuropeptide HA
- Substrate Specificity and Inhibitor Studies of a Membrane-Bound Ganglioside Sialidase Isolated from Human Brain Tissue
- Specificity Determinants in the Interaction of Apolipoprotein(a) Kringles with Tetranectin and LDL
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