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Protein–Protein Interaction Regulates the Direction of Catalysis and Electron Transfer in a Redox Enzyme Complex
[Image: see text] Protein–protein interactions are well-known to regulate enzyme activity in cell signaling and metabolism. Here, we show that protein–protein interactions regulate the activity of a respiratory-chain enzyme, CymA, by changing the direction or bias of catalysis. CymA, a member of the...
Autores principales: | , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Chemical Society
2013
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3823026/ https://www.ncbi.nlm.nih.gov/pubmed/23799249 http://dx.doi.org/10.1021/ja405072z |
Sumario: | [Image: see text] Protein–protein interactions are well-known to regulate enzyme activity in cell signaling and metabolism. Here, we show that protein–protein interactions regulate the activity of a respiratory-chain enzyme, CymA, by changing the direction or bias of catalysis. CymA, a member of the widespread NapC/NirT superfamily, is a menaquinol-7 (MQ-7) dehydrogenase that donates electrons to several distinct terminal reductases in the versatile respiratory network of Shewanella oneidensis. We report the incorporation of CymA within solid-supported membranes that mimic the inner membrane architecture of S. oneidensis. Quartz-crystal microbalance with dissipation (QCM-D) resolved the formation of a stable complex between CymA and one of its native redox partners, flavocytochrome c(3) (Fcc(3)) fumarate reductase. Cyclic voltammetry revealed that CymA alone could only reduce MQ-7, while the CymA-Fcc(3) complex catalyzed the reaction required to support anaerobic respiration, the oxidation of MQ-7. We propose that MQ-7 oxidation in CymA is limited by electron transfer to the hemes and that complex formation with Fcc(3) facilitates the electron-transfer rate along the heme redox chain. These results reveal a yet unexplored mechanism by which bacteria can regulate multibranched respiratory networks through protein–protein interactions. |
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