PixE promotes dark oligomerization of the BLUF photoreceptor PixD
Tóm tắt
Cyanobacteria perceive and move (phototax) in response to blue light. In this study, we demonstrate that the PixD blue light-sensing using FAD (BLUF) photoreceptor that governs this response undergoes changes in oligomerization state upon illumination. Under dark conditions we observed that PixD forms a large molecular weight complex with another protein called PixE. Stoicheometric analyses, coupled with sedimentation equilibrium and size exclusion chromatography, demonstrates that PixE drives aggregation of PixD dimers into a stable PixD 10 —PixE 5 complex under dark conditions. Illumination of a flavin chromophore in PixD destabilizes the PixD 10 –PixE 5 complex into monomers of PixE and dimers of PixD. A crystallographic structure of PixD, coupled with Gibbs free energy calculation between interacting faces of PixD, lends to a model in which a light induces a conformational change in a critical PixD-interfacing loop that results in destabilization of the PixD 10 –PixE 5 complex.
Từ khóa
Tài liệu tham khảo
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