Stanford Advisors

All Publications

  • De novo design of proteins housing excitonically coupled chlorophyll special pairs NATURE CHEMICAL BIOLOGY Ennist, N. M., Wang, S., Kennedy, M. A., Curti, M., Sutherland, G. A., Vasilev, C., Redler, R. L., Maffeis, V., Shareef, S., Sica, A. V., Hua, A., Deshmukh, A. P., Moyer, A. P., Hicks, D. R., Swartz, A. Z., Cacho, R. A., Novy, N., Bera, A. K., Kang, A., Sankaran, B., Johnson, M. P., Phadkule, A., Reppert, M., Ekiert, D., Bhabha, G., Stewart, L., Caram, J. R., Stoddard, B. L., Romero, E., Hunter, C., Baker, D. 2024


    Natural photosystems couple light harvesting to charge separation using a 'special pair' of chlorophyll molecules that accepts excitation energy from the antenna and initiates an electron-transfer cascade. To investigate the photophysics of special pairs independently of the complexities of native photosynthetic proteins, and as a first step toward creating synthetic photosystems for new energy conversion technologies, we designed C2-symmetric proteins that hold two chlorophyll molecules in closely juxtaposed arrangements. X-ray crystallography confirmed that one designed protein binds two chlorophylls in the same orientation as native special pairs, whereas a second designed protein positions them in a previously unseen geometry. Spectroscopy revealed that the chlorophylls are excitonically coupled, and fluorescence lifetime imaging demonstrated energy transfer. The cryo-electron microscopy structure of a designed 24-chlorophyll octahedral nanocage with a special pair on each edge closely matched the design model. The results suggest that the de novo design of artificial photosynthetic systems is within reach of current computational methods.

    View details for DOI 10.1038/s41589-024-01626-0

    View details for Web of Science ID 001237780900001

    View details for PubMedID 38831036

    View details for PubMedCentralID 3098534

  • Near-atomic-resolution structure of J-aggregated helical light-harvesting nanotubes NATURE CHEMISTRY Deshmukh, A. P., Zheng, W., Chuang, C., Bailey, A. D., Williams, J. A., Sletten, E. M., Egelman, E. H., Caram, J. R. 2024


    Cryo-electron microscopy has delivered a resolution revolution for biological self-assemblies, yet only a handful of structures have been solved for synthetic supramolecular materials. Particularly for chromophore supramolecular aggregates, high-resolution structures are necessary for understanding and modulating the long-range excitonic coupling. Here, we present a 3.3 Å structure of prototypical biomimetic light-harvesting nanotubes derived from an amphiphilic cyanine dye (C8S3-Cl). Helical 3D reconstruction directly visualizes the chromophore packing that controls the excitonic properties. Our structure clearly shows a brick layer arrangement, revising the previously hypothesized herringbone arrangement. Furthermore, we identify a new non-biological supramolecular motif-interlocking sulfonates-that may be responsible for the slip-stacked packing and J-aggregate nature of the light-harvesting nanotubes. This work shows how independently obtained native-state structures complement photophysical measurements and will enable accurate understanding of (excitonic) structure-function properties, informing materials design for light-harvesting chromophore aggregates.

    View details for DOI 10.1038/s41557-023-01432-6

    View details for Web of Science ID 001156893700002

    View details for PubMedID 38316987

    View details for PubMedCentralID 2919932