book chapter published yes Ben Clifton author Jason Whitfield author Inmaculada Sanchez Romero author 3D9C5D30-F248-11E8-B48F-1D18A9856A87 Michel Herde author Christian Henneberger author Harald L Janovjak author 33BA6C30-F248-11E8-B48F-1D18A9856A870000-0002-8023-9315 Colin Jackson author ViktorStein editor HaJa department In situ real-time imaging of neurotransmitter signaling using designer optical sensors project Small molecule biosensors based on Forster resonance energy transfer (FRET) enable small molecule signaling to be monitored with high spatial and temporal resolution in complex cellular environments. FRET sensors can be constructed by fusing a pair of fluorescent proteins to a suitable recognition domain, such as a member of the solute-binding protein (SBP) superfamily. However, naturally occurring SBPs may be unsuitable for incorporation into FRET sensors due to their low thermostability, which may preclude imaging under physiological conditions, or because the positions of their N- and C-termini may be suboptimal for fusion of fluorescent proteins, which may limit the dynamic range of the resulting sensors. Here, we show how these problems can be overcome using ancestral protein reconstruction and circular permutation. Ancestral protein reconstruction, used as a protein engineering strategy, leverages phylogenetic information to improve the thermostability of proteins, while circular permutation enables the termini of an SBP to be repositioned to maximize the dynamic range of the resulting FRET sensor. We also provide a protocol for cloning the engineered SBPs into FRET sensor constructs using Golden Gate assembly and discuss considerations for in situ characterization of the FRET sensors. Springer2017 eng 1064-374510.1007/978-1-4939-6940-1_5 159671 - 87 B. Clifton, J. Whitfield, I. Sanchez-Romero, M. Herde, C. Henneberger, H.L. Janovjak, C. Jackson, in:, V. Stein (Ed.), Synthetic Protein Switches, Springer, 2017, pp. 71–87. Clifton, Ben, Jason Whitfield, Inmaculada Sanchez-Romero, Michel Herde, Christian Henneberger, Harald L Janovjak, and Colin Jackson. “Ancestral Protein Reconstruction and Circular Permutation for Improving the Stability and Dynamic Range of FRET Sensors.” In <i>Synthetic Protein Switches</i>, edited by Viktor Stein, 1596:71–87. Synthetic Protein Switches. Springer, 2017. <a href="https://doi.org/10.1007/978-1-4939-6940-1_5">https://doi.org/10.1007/978-1-4939-6940-1_5</a>. Clifton B, Whitfield J, Sanchez-Romero I, et al. Ancestral protein reconstruction and circular permutation for improving the stability and dynamic range of FRET sensors. In: Stein V, ed. <i>Synthetic Protein Switches</i>. Vol 1596. Synthetic Protein Switches. Springer; 2017:71-87. doi:<a href="https://doi.org/10.1007/978-1-4939-6940-1_5">10.1007/978-1-4939-6940-1_5</a> B. Clifton <i>et al.</i>, “Ancestral protein reconstruction and circular permutation for improving the stability and dynamic range of FRET sensors,” in <i>Synthetic Protein Switches</i>, vol. 1596, V. Stein, Ed. Springer, 2017, pp. 71–87. Clifton B, Whitfield J, Sanchez-Romero I, Herde M, Henneberger C, Janovjak HL, Jackson C. 2017.Ancestral protein reconstruction and circular permutation for improving the stability and dynamic range of FRET sensors. In: Synthetic Protein Switches. Methods in Molecular Biology, vol. 1596, 71–87. Clifton, Ben, et al. “Ancestral Protein Reconstruction and Circular Permutation for Improving the Stability and Dynamic Range of FRET Sensors.” <i>Synthetic Protein Switches</i>, edited by Viktor Stein, vol. 1596, Springer, 2017, pp. 71–87, doi:<a href="https://doi.org/10.1007/978-1-4939-6940-1_5">10.1007/978-1-4939-6940-1_5</a>. Clifton, B., Whitfield, J., Sanchez-Romero, I., Herde, M., Henneberger, C., Janovjak, H. L., &#38; Jackson, C. (2017). Ancestral protein reconstruction and circular permutation for improving the stability and dynamic range of FRET sensors. In V. Stein (Ed.), <i>Synthetic Protein Switches</i> (Vol. 1596, pp. 71–87). Springer. <a href="https://doi.org/10.1007/978-1-4939-6940-1_5">https://doi.org/10.1007/978-1-4939-6940-1_5</a> 9572018-12-11T11:49:24Z2025-07-10T12:01:52Z