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Interactions between the soluble domain I of nicotinamide nucleotide transhydrogenase from Rhodospirillum rubrum and transhydrogenase from Escherichia coliстатья
- Авторы: Bizouarn Tania, Fjellström Ola, Axelsson Magnus, Korneenko Tatyana V., Pestov Nikolay B., Ivanova Maria V., Egorov Maxim V., Shakhparonov Michail, Rydström Jan
- Журнал: European Journal of Biochemistry
- Том: 267
- Номер: 11
- Год издания: 2000
- Первая страница: 3281
- Последняя страница: 3288
- DOI: 10.1046/j.1432-1327.2000.01358.x
- Аннотация: Nicotinamide nucleotide transhydrogenase from Escherichia coli is composed of two subunits, the alpha and the beta subunits, each of which contains a hydrophilic domain, domain I and III, respectively, as well as several transmembrane helices, collectively denoted domain II. The interactions between domain I from Rhodospirillum rubrum (rrI) and the intact or the protease-treated enzyme from E. coli was investigated using the separately expressed and purified domain I from R. rubrum, and His-tagged intact and trypsin-treated E. coli transhydrogenase. Despite harsh treatments with, e.g. detergents and denaturing agents, the alpha and beta subunits remained tightly associated. A monoclonal antibody directed towards the alpha subunit was strongly inhibitory, an effect that was relieved by added rrI. In addition, rrI also reactivated the trypsin-digested E. coli enzyme in which domain I had been partly removed. This suggests that the hydrophilic domains I and III are not in permanent contact but are mobile during catalysis while being anchored to domain II. Replacement of domain I of intact, as well as trypsin-digested, E. coli transhydrogenase with rrI resulted in a markedly different pH dependence of the cyclic reduction of 3-acetyl-pyridine-NAD+ by NADH in the presence of NADP(H), suggesting that the protonation of one or more protonable groups in domain I is controlling this reaction. The reverse reaction and proton pumping showed a less pronounced change in pH dependence, demonstrating the regulatory role of domain II in these reactions.
- Добавил в систему: Коноплева Мария Вениаминовна