1. Modulation of Electron Transfer Branches by Atrazine and Triazine Herbicides in Photosynthetic Reaction Centers.
- Author
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Nishikawa G, Saito K, and Ishikita H
- Subjects
- Electron Transport, Oxidation-Reduction, Models, Molecular, Rhodobacter sphaeroides metabolism, Crystallography, X-Ray, Herbicides chemistry, Herbicides metabolism, Atrazine chemistry, Atrazine metabolism, Triazines chemistry, Triazines metabolism, Photosynthetic Reaction Center Complex Proteins metabolism, Photosynthetic Reaction Center Complex Proteins chemistry
- Abstract
Quinone analogue molecules, functioning as herbicides, bind to the secondary quinone site, Q
B , in type-II photosynthetic reaction centers, including those from purple bacteria (PbRC). Here, we investigated the impact of herbicide binding on electron transfer branches, using herbicide-bound PbRC crystal structures and employing the linear Poisson-Boltzmann equation. In contrast to urea and phenolic herbicides [Fufezan, C. Biochemistry 2005, 44, 12780-12789], binding of atrazine and triazine did not cause significant changes in the redox-potential ( Em ) values of the primary quinone (QA difference at the bacteriopheophytin in the electron transfer inactive branch (H Em difference at the bacteriopheophytin in the electron transfer inactive branch (HM ) was observed between the S -mediated link between the electron transfer inactive H R (+)-triazine-bound PbRC structures. This discrepancy is linked to variations in the protonation pattern of the tightly coupled Glu-L212 and Glu-H177 pairs, crucial components of the proton uptake pathway in native PbRC. These findings suggest the existence of a QB -mediated link between the electron transfer inactive HM and the proton uptake pathway in PbRCs.- Published
- 2024
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