Research project
Respiratory-chain enzymes
Many metalloenzymes that are key to bioenergetics are membrane enzymes, with canonical examples the complexes I, II, III and IV in the mitochondrial inner membrane. To study these enzymes in a native-like lipid membrane environment, we aim to develop novel bioelectrochemical techniques.
- Contact
- Lars Jeuken
Many respiratory-chain enzymes convert lipophilic quinones, like co-enzyme Q in the mitochondrial membrane. As these quinones are not water-soluble, they are experimentally difficult to handle, and many enzyme assays use water-soluble quinone analogues instead. We have developed an electrochemical system in which a lipid membrane is either ‘tethered’ or adsorbed to an electrode and the native quinone-pool is electrochemically reduced or oxidised. Enzyme turn-over is conveniently monitored as an electrochemical current and the action of enzyme substrates and inhibitors can thus be directly measured. By adsorbing intact proteoliposomes on a surface, it is also possible to simultaneously measure proton transport is in fluorescence microscopy.
Cytochrome bd as an antibacterial target
Ever since the FDA approved the drug bedaquiline, which inhibits the activity the F0F1-ATP synthase, for the treatment of tuberculosis in 2012, respiratory-chain enzymes have been an active target space for the discovery of new antibiotics. Bacterial cytochrome bd, which is a terminal oxidase, has been of special interest as there is no human homologue of this in enzyme in mitochondria. Cytochrome bd oxidises the quinone pool in a variety of bacterial species, typically under oxygen limiting conditions. Using our membrane-modified electrodes, we are studying the interaction cytochrome bd with the quinone pool.
Key publications
Nakatani Y., Shimaki Y., Dutta D., Muench S.P., Ireton K., Cook G.M. & Jeuken L.J.C. (2019), Unprecedented Properties of Phenothiazines Unraveled by a NDH-2 Bioelectrochemical Assay Platform, Journal of the American Chemical Society 142: 1311-1320. DOI: 10.1021/jacs.9b10254
Heath G.R., Li M., Rong H., Radu V., Frielingsdorf S., Lenz O., Butt J.N. & Jeuken L.J.C. (2017), Multilayered Lipid Membrane Stacks for Biocatalysis Using Membrane Enzymes, Advanced Functional Materials 27: 1606265. DOI: 10.1002/adfm.201606265
Li M. Jørgensen S.K. McMillan D.G.G. Krzemiński Ł. Daskalakis N.N. Partanen R.H. Tutkus M. Tuma R. Stamou D. Hatzakis N.S. Jeuken L.J.C. (2015), Single Enzyme Experiments Reveal a Long-Lifetime Proton Leak State in a Heme-Copper Oxidase, Journal of the American Chemical Society 137: 16055-16063. DOI: 10.1021/jacs.5b08798
Radu V., Frielingsdorf S., Evans S.D., Lenz O. & Jeuken L.J.C. (2014), Enhanced Oxygen-Tolerance of the Full Heterotrimeric Membrane-Bound [NiFe]-Hydrogenase of Ralstonia eutropha, Journal of the American Chemical Society 136: 8512-8515. DOI: 10.1021/ja503138p