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Reduction of Synthetic Ubiquinone QT Catalyzed by Bovine Mitochondrial Complex I Is Decoupled from Proton Translocation

, : Reduction of Synthetic Ubiquinone QT Catalyzed by Bovine Mitochondrial Complex I Is Decoupled from Proton Translocation. Biochemistry 55(3): 470-481

We previously succeeded in site-specific chemical modifications of the inner part of the quinone binding pocket of bovine mitochondrial complex I through ligand-directed tosylate (LDT) chemistry using specific inhibitors as high-affinity ligands for the enzyme [Masuya, T., et al. (2014) Biochemistry 53, 2304-2317, 7816-7823]. To investigate whether a short-chain ubiquinone, in place of these specific inhibitors, serves as a ligand for LDT chemistry, we herein synthesized a LDT reagent QT possessing ubiquinone scaffold and performed LDT chemistry with bovine heart submitochondrial particles (SMP). Detailed proteomic analyses revealed that QT properly guides the tosylate group into the quinone binding pocket and transfers a terminal alkyne to nucleophilic amino acids His150 and Asp160 in the 49 kDa subunit. This result clearly indicates that QT occupies the inner part of the quinone binding pocket. Nevertheless, we noted that QT is a unique electron acceptor from complex I distinct from typical short-chain ubiquinones such as ubiquinone-1 (Q1) for several reasons; for example, QT reduction in NADH-QT oxidoreduction was almost completely insensitive to quinone-site inhibitors (such as bullatacin and piericidin A), and this reaction did not produce a membrane potential. On the basis of detailed comparisons of the electron transfer features between QT and typical short-chain quinones, we conclude that QT may accept electrons from an N2 cluster at a position different from that of typical short-chain quinones because of its unique side-chain structure; accordingly, QT reduction is unable to induce putative structural changes inside the quinone binding pocket, which are critical for driving proton translocation. Thus, QT is the first ubiquinone analogue, to the best of our knowledge, the catalytic reduction of which is decoupled from proton translocation through the membrane domain. Implications for mechanistic studies on QT are also discussed.


PMID: 26701224

DOI: 10.1021/acs.biochem.5b01090

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Mwipatayi, B.P.; Jeffery, P.; Beningfield, S.J.; Motale, P.; Tunnicliffe, J.; Navsaria, P.H., 2004: Management of extra-cranial vertebral artery injuries. To review the management of vertebral artery injuries, and the impact of pre-operative angiography. A retrospective review was conducted of all patients with vertebral artery (VA) injuries admitted to Groote Schuur Hospital, Cape Town between Janu...

Sharma, K.K.; Gupta, V.K., 1994: Influence of fungicides on spore germination, sporulation and control of apple powdery mildew. Six fungicides namely carbendazim, bitertanol, triadimefon, tridemorph, triforine and thiophanate methyl significantly inhibited spore germination of Podosphaera leucotricha and reduced germ tube length. The maximum inhibition (94%) was obtained i...

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Bers D.M.; Langer G.A., 1979: Effects of uncoupling cations on sarcolemmal calcium ion binding and on functional responses of intact cardiac muscle. Federation Proceedings 38(3 PART 1): 889

Dickey Parke A., 1989: Overview of development geology. AAPG Studies in Geology 28: 1-2

Lin, Z.X. (Lin, C.H), 1981: Feasibility studies on the development of strawberry production in tropical areas. From trials of 11 varieties for yield, sugar content, maturity and heat tolerance, it is concluded that the variety Sunshian is the most suitable for cultivation in the Kaopin area of Taiwan. It flowers early and bears large, bright red fruit with...

Pandey, D.K.; Fursich, F.T.eodor.; Heinze, M., 1996: Contributions to the Jurassic of Kachchh, western India. 5. The bivalve fauna. Part 2. Subclass Anomalodesmata. Beringeria, 18: 51-87

Wilson, J.X.; Sawai, H.; Kikuchi, M.; Kubokawa, K.; Ishii, S., 1995: Circulating catecholamine and glucose concentrations in Japanese toads (Bufo japonicus) during the breeding season. We investigated the relationship between catecholamine neurohormones and glucose during seasonal reproductive activity in Japanese toads (Bufo japonicus). Field studies found that plasma epinephrine concentration increased as toads migrated to the...

Milić, N., 1977: The beginning and development of hematology and blood transfusion in Croatia. Bilten Za Hematologiju i Transfuziju 5(1): 75-77