PixE promotes dark oligomerization of the BLUF photoreceptor PixD

Proceedings of the National Academy of Sciences of the United States of America - Tập 105 Số 33 - Trang 11715-11719 - 2008
Hua Yuan1, Carl E. Bauer1
1Department of Biology, Indiana University, Bloomington, IN 47405

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


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Proceedings of the National Academy of Sciences of the United States of America

Tập 105 Số 33

11715-11719

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