Disaccharide trehalose has been proven in many cases to be particularly effective in preserving the functional and structural integrity of biological macromolecules. In this work, we studied its effect on the electron transfer reactions that occur in the chromatophores of the photosynthetic bacterium Cereibacter sphaeroides. In the presence of a high concentration of trehalose, following the activation of the photochemistry by flashes of light, a slowdown of the electrogenic reactions related to the activity of the photosynthetic reaction center and cytochtome (cyt) bc1 complexes is observable. The kinetics of the third phase of the electrochromic carotenoid shift, due to electrogenic events linked to the reduction in cyt bH heme via the low-potential branch of the cyt bc1 complex and its oxidation by quinone molecule on the Qi site, is about four times slower in the presence of trehalose. In parallel, the reduction in oxidized cyt (c1 + c2) and high-potential cyt bH are strongly slowed down, suggesting that the disaccharide interferes with the electron transfer reactions of the high-potential branch of the bc1 complex. A slowing effect of trehalose on the kinetics of the electrogenic protonation of the secondary quinone acceptor QB in the reaction center complex, measured by direct electrometrical methods, was also found, but was much less pronounced. The direct detection of carbohydrate content indicates that trehalose, at high concentrations, permeates the membrane of chromatophores. The possible mechanisms underlying the observed effect of trehalose on the electron/proton transfer process are discussed in terms of trehalose’s propensity to form strong hydrogen bonds with its surroundings.
Trehalose Interferes with the Photosynthetic Electron Transfer Chain of Cereibacter (Rhodobacter) sphaeroides Permeating the Bacterial Chromatophore Membrane
G. Venturoli,M. Mamedov,L. Vitukhnovskaya,A. Y. Semenov,F. Francia
Published 2024 in International Journal of Molecular Sciences
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- Publication year
2024
- Venue
International Journal of Molecular Sciences
- Publication date
2024-12-01
- Fields of study
Biology, Medicine, Chemistry, Environmental Science
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Semantic Scholar, PubMed
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