期刊
REDOX BIOLOGY
卷 16, 期 -, 页码 209-214出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.redox.2018.02.004
关键词
FAD; Respiratory chain; Flavoprotein; Electron transfer; Bacterial respiration; Kinetics
资金
- Fundacao para a Ciencia e a Tecnologia [PD/BD/113985/2015, PD/BD/128213/2016, PD/00133/2012, IF/01507/2015]
- FEDER [LISBOA-01-0145-FEDER-007660]
- FCT - Fundacao para a Ciencia e a Tecnologia
- national funds through FCT - Fundacao para a Ciencia e a Tecnologia
- FCT, Portugal [UID/MULTI/04046/2013]
- Fundação para a Ciência e a Tecnologia [PD/BD/128213/2016, PD/BD/113985/2015] Funding Source: FCT
Type-II NADH:quinone oxidoreductases (NDH-2s) are membrane proteins involved in respiratory chains and the only enzymes with NADH:quinone oxidoreductase activity expressed in Staphylococcus aureus (S. aureus), one of the most common causes of clinical infections. NDH-2s are members of the two-Dinucleotide Binding Domains Flavoprotein (tDBDF) superfamily, having a flavin adenine dinucleotide, FAD, as prosthetic group and NAD(P)H as substrate. The establishment of a Charge-Transfer Complex (CTC) between the isoalloxazine ring of the reduced flavin and the nicotinamide ring of NAD + in NDH-2 was described, and in this work we explored its role in the kinetic mechanism using different electron donors and electron acceptors. We observed that CTC slows down the rate of the second half reaction (quinone reduction) and determines the effect of HQNO, an inhibitor. Also, protonation equilibrium simulations clearly indicate that the protonation probability of an important residue for proton transfer to the active site (D302) is influenced by the presence of the CTC. We propose that CTC is critical for the overall mechanism of NDH-2 and possibly relevant to keep a low quinol/quinone ratio and avoid excessive ROS production in vivo.
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