Proton transfer and nitric oxide reduction in heme-copper oxidases


Project leader


Funding source

Swedish Research Council - Vetenskapsrådet (VR)


Project Details

Start date: 01/01/2016
End date: 31/12/2019
Funding: 3000000 SEK


Description

Bacterial NO-reductases (NOR) are integral membrane proteins that reduce the toxic gas nitric oxide (NO) to dinitrous oxide (N2O) (2NO+2e-+2H+->N2O+H2O). NORs are divergent members of the super-family of oxygen-reducing, proton pumping, heme-copper oxidases (HCuOs), to which the mitochondrial cytochrome c oxidase (mCcO) also belongs. Despite belonging to the same family, the function of the NORs is very different from other HCuOs in that NORs do not conserve the free energy available from NO reduction by creating a proton gradient over the membrane. The closest relatives to NOR among the HCuOs are the cbb3 oxidases, which have a high oxygen affinity and are found exclusively in bacteria, often pathogens. The cbb3 oxidases also show NO-reduction activity in contrast to the mCcO and NORs can reduce O2. The project aims at elucidating the structure-function relationships in the bacterial NORs and cbb3 oxidases, with special focus on proton transfer pathways, mechanisms and vectoriality. We expect to gain insight also into the evolution of the heme-copper oxidase superfamily. Our studies involve techniques from molecular biology to biophysics; e.g. site-directed mutagenesis, protein purification optimisations, reconstitution into membrane mimetic systems, and time-resolved optical spectroscopy/electrometry of single catalytic turnovers.


Last updated on 2017-01-06 at 09:19

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