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  • Perspective
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Structure- and mechanism-guided design of single fluorescent protein-based biosensors

Abstract

Intensiometric genetically encoded biosensors, based on allosteric modulation of the fluorescence of a single fluorescent protein, are powerful tools for enabling imaging of neural activities and other cellular biochemical events. The archetypical example of such biosensors is the GCaMP series of Ca2+ biosensors, which have been steadily improved over the past two decades and are now indispensable tools for neuroscience. However, no other biosensors have reached levels of performance, or had revolutionary impacts within specific disciplines, comparable to that of the Ca2+ biosensors. Of the many reasons why this has been the case, a critical one has been a general black-box view of biosensor structure and mechanism. With this Perspective, we aim to summarize what is known about biosensor structure and mechanisms and, based on this foundation, provide guidelines to accelerate the development of a broader range of biosensors with performance comparable to that of the GCaMP series.

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Fig. 1: Single FP-based biosensors and topologies used in biosensor creation.
Fig. 2: Representation of the gate post and bulge residues in FPs derived from different species.
Fig. 3: Gate posts, bulges and adjacent sequences in selected FPs.
Fig. 4: Representative X-ray crystal structures of biosensors.
Fig. 5: Conservation of bulge residue Glu144 in RFP- and cpRFP-based biosensors.
Fig. 6: GFP- and RFP-based biosensor structures provide insight into the mechanism of the fluorescence response.

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References

  1. Greenwald, E. C., Mehta, S. & Zhang, J. Genetically encoded fluorescent biosensors illuminate the spatiotemporal regulation of signaling networks. Chem. Rev. 118, 11707–11794 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  2. Lavis, L. D. Teaching old dyes new tricks: biological probes built from fluoresceins and rhodamines. Annu. Rev. Biochem. 86, 825–843 (2017).

    Article  CAS  PubMed  Google Scholar 

  3. Smith, B. R. & Gambhir, S. S. Nanomaterials for in vivo imaging. Chem. Rev. 117, 901–986 (2017).

    Article  CAS  PubMed  Google Scholar 

  4. Miyawaki, A. et al. Fluorescent indicators for Ca2+ based on green fluorescent proteins and calmodulin. Nature 388, 882–887 (1997).

    Article  CAS  PubMed  Google Scholar 

  5. Baird, G. S., Zacharias, D. A. & Tsien, R. Y. Circular permutation and receptor insertion within green fluorescent proteins. Proc. Natl Acad. Sci. USA 96, 11241–11246 (1999). This landmark paper describes the discovery of the GFP insertion site adjacent to residue 145, describes the first examples of single FP-based biosensors (Ca2+ and Zn2+) and summarizes the various possible topologies for single FP-based indicators.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  6. Kostyuk, A. I., Demidovich, A. D., Kotova, D. A., Belousov, V. V. & Bilan, D. S. Circularly permuted fluorescent protein-based indicators: history, principles, and classification. Int. J. Mol. Sci. 20, 4200 (2019).

    Article  PubMed Central  CAS  Google Scholar 

  7. Kaczmarski, J. A., Mitchell, J. A., Spence, M. A., Vongsouthi, V. & Jackson, C. J. Structural and evolutionary approaches to the design and optimization of fluorescence-based small molecule biosensors. Curr. Opin. Struct. Biol. 57, 31–38 (2019).

    Article  CAS  PubMed  Google Scholar 

  8. Carlson, H. J. & Campbell, R. E. Genetically encoded FRET-based biosensors for multiparameter fluorescence imaging. Curr. Opin. Biotechnol. 20, 19–27 (2009).

    Article  CAS  PubMed  Google Scholar 

  9. Boffi, J. C., Knabbe, J., Kaiser, M. & Kuner, T. KCC2-dependent steady-state intracellular chloride concentration and pH in cortical layer 2/3 neurons of anesthetized and awake mice. Front. Cell. Neurosci. 12, 7 (2018).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  10. Mehta, S. et al. Single-fluorophore biosensors for sensitive and multiplexed detection of signalling activities. Nat. Cell Biol. 20, 1215–1225 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  11. Zhao, Y. et al. An expanded palette of genetically encoded Ca2+ indicators. Science 333, 1888–1891 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  12. Wu, J. et al. A long Stokes shift red fluorescent Ca2+ indicator protein for two-photon and ratiometric imaging. Nat. Commun. 5, 5262 (2014).

    Article  CAS  PubMed  Google Scholar 

  13. Barykina, N. V. et al. FGCaMP7, an improved version of fungi-based ratiometric calcium indicator for in vivo visualization of neuronal activity. Int. J. Mol. Sci. 21, 3012 (2020).

    Article  CAS  PubMed Central  Google Scholar 

  14. Su, S. et al. Genetically encoded calcium indicator illuminates calcium dynamics in primary cilia. Nat. Methods 10, 1105–1107 (2013).

    Article  CAS  PubMed  Google Scholar 

  15. Ast, C. et al. Ratiometric Matryoshka biosensors from a nested cassette of green- and orange-emitting fluorescent proteins. Nat. Commun. 8, 431 (2017).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  16. Nakai, J., Ohkura, M. & Imoto, K. A high signal-to-noise Ca2+ probe composed of a single green fluorescent protein. Nat. Biotechnol. 19, 137–141 (2001). Together with Nagai et al.33, this paper describes the development of the first cpFP-based Ca2+ genetically encoded calcium indicators (GECIs).

    Article  CAS  PubMed  Google Scholar 

  17. Tallini, Y. N. et al. Imaging cellular signals in the heart in vivo: cardiac expression of the high-signal Ca2+ indicator GCaMP2. Proc. Natl Acad. Sci. USA 103, 4753–4758 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  18. Tian, L. et al. Imaging neural activity in worms, flies and mice with improved GCaMP calcium indicators. Nat. Methods 6, 875–881 (2009). This paper reports the first demonstration of Ca2+ imaging of neuronal activity in awake behaving mice using the single FP-based GECI GCaMP3.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  19. Akerboom, J. et al. Optimization of a GCaMP calcium indicator for neural activity imaging. J. Neurosci. 32, 13819–13840 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  20. Chen, T.-W. et al. Ultrasensitive fluorescent proteins for imaging neuronal activity. Nature 499, 295–300 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  21. Dana, H. et al. High-performance calcium sensors for imaging activity in neuronal populations and microcompartments. Nat. Methods 16, 649–657 (2019).

    Article  CAS  PubMed  Google Scholar 

  22. Patriarchi, T. et al. Ultrafast neuronal imaging of dopamine dynamics with designed genetically encoded sensors. Science 360, eaat4422 (2018). Together with Sun et al.23, this paper describes the development of the first single FP-based dopamine biosensors using a GPCR as the sensing moiety.

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  23. Sun, F. et al. A genetically encoded fluorescent sensor enables rapid and specific detection of dopamine in flies, fish, and mice. Cell 174, 481–496.e19 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  24. Jing, M. et al. A genetically encoded fluorescent acetylcholine indicator for in vitro and in vivo studies. Nat. Biotechnol. 36, 726–737 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  25. Feng, J. et al. A genetically encoded fluorescent sensor for rapid and specific in vivo detection of norepinephrine. Neuron 102, 745–761.e8 (2019).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  26. Shivange, A. V. et al. Determining the pharmacokinetics of nicotinic drugs in the endoplasmic reticulum using biosensors. J. Gen. Physiol. 151, 738–757 (2019).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  27. Helassa, N. et al. Ultrafast glutamate sensors resolve high-frequency release at Schaffer collateral synapses. Proc. Natl Acad. Sci. USA 115, 5594–5599 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  28. Marvin, J. S. et al. Stability, affinity, and chromatic variants of the glutamate sensor iGluSnFR. Nat. Methods 15, 936–939 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  29. Marvin, J. S. et al. A genetically encoded fluorescent sensor for in vivo imaging of GABA. Nat. Methods 16, 763–770 (2019).

    Article  CAS  PubMed  Google Scholar 

  30. Sun, F. et al. Next-generation GRAB sensors for monitoring dopaminergic activity in vivo. Nat. Methods 17, 1156–1166 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  31. Borden, P. M. et al. A fast genetically encoded fluorescent sensor for faithful in vivo acetylcholine detection in mice, fish, worms and flies. Preprint at bioRxiv https://doi.org/10.1101/2020.02.07.939504 (2020).

  32. Zhang, S., Li, X., Drobizhev, M. & Ai, H. A fast high-affinity fluorescent serotonin biosensor engineered from a tick lipocalin. Preprint at bioRxiv https://doi.org/10.1101/2020.04.18.048397 (2020).

  33. Nagai, T., Sawano, A., Park, E. S. & Miyawaki, A. Circularly permuted green fluorescent proteins engineered to sense Ca2+. Proc. Natl Acad. Sci. USA 98, 3197–3202 (2001).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  34. Belousov, V. V. et al. Genetically encoded fluorescent indicator for intracellular hydrogen peroxide. Nat. Methods 3, 281–286 (2006).

    Article  CAS  PubMed  Google Scholar 

  35. Souslova, E. A. et al. Single fluorescent protein-based Ca2+ sensors with increased dynamic range. BMC Biotechnol. 7, 37 (2007).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  36. Nausch, L. W. M., Ledoux, J., Bonev, A. D., Nelson, M. T. & Dostmann, W. R. Differential patterning of cGMP in vascular smooth muscle cells revealed by single GFP-linked biosensors. Proc. Natl Acad. Sci. USA 105, 365–370 (2008).

    Article  CAS  PubMed  Google Scholar 

  37. Berg, J., Hung, Y. P. & Yellen, G. A genetically encoded fluorescent reporter of ATP:ADP ratio. Nat. Methods 6, 161–166 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  38. Wu, J. et al. Genetically encoded glutamate indicators with altered color and topology. ACS Chem. Biol. 13, 1832–1837 (2018). Together with Qian et al.39, this paper demonstrates that it is possible to convert a biosensor based oninsertion of a cpFP into a sensing domaininto a biosensor based oninsertion of a permuted sensing domain into an FP’.

    Article  CAS  PubMed  Google Scholar 

  39. Qian, Y., Rancic, V., Wu, J., Ballanyi, K. & Campbell, R. E. A bioluminescent Ca2+ indicator based on a topological variant of GCaMP6s. ChemBioChem 20, 516–520 (2019).

    Article  CAS  PubMed  Google Scholar 

  40. Molina, R. S. et al. Understanding the fluorescence change in red genetically encoded calcium ion indicators. Biophys. J. 116, 1873–1886 (2019).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  41. Wardill, T. J. et al. A neuron-based screening platform for optimizing genetically-encoded calcium indicators. PLoS ONE 8, e77728 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  42. Ormö, M. et al. Crystal structure of the Aequorea victoria green fluorescent protein. Science 273, 1392–1395 (1996).

    Article  PubMed  Google Scholar 

  43. Tsien, R. Y. The green fluorescent protein. Annu. Rev. Biochem. 67, 509–544 (1998).

    Article  CAS  PubMed  Google Scholar 

  44. Pedelacq, J. D., Cabantous, S., Tran, T., Terwilliger, T. C. & Waldo, G. S. Engineering and characterization of a superfolder green fluorescent protein. Nat. Biotechnol. 24, 79–88 (2006).

    Article  CAS  PubMed  Google Scholar 

  45. Akerboom, J. et al. Genetically encoded calcium indicators for multi-color neural activity imaging and combination with optogenetics. Front. Mol. Neurosci. 6, 2 (2013). This paper reports a multi-colored set of GECIs and the X-ray crystal structures of R-GECO1 and RCaMP1, which provided the first mechanistic insight into RFP-based GECIs.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  46. Chattoraj, M., King, B. A., Bublitz, G. U. & Boxer, S. G. Ultra-fast excited state dynamics in green fluorescent protein: multiple states and proton transfer. Proc. Natl Acad. Sci. USA 93, 8362–8367 (1996).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  47. Kogure, T. et al. A fluorescent variant of a protein from the stony coral Montipora facilitates dual-color single-laser fluorescence cross-correlation spectroscopy. Nat. Biotechnol. 24, 577–581 (2006).

    Article  CAS  PubMed  Google Scholar 

  48. Barnett, L. M., Hughes, T. E. & Drobizhev, M. Deciphering the molecular mechanism responsible for GCaMP6m’s Ca2+-dependent change in fluorescence. PLoS ONE 12, e0170934 (2017).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  49. Topell, S., Hennecke, J. & Glockshuber, R. Circularly permuted variants of the green fluorescent protein. FEBS Lett. 457, 283–289 (1999).

    Article  CAS  PubMed  Google Scholar 

  50. Fosque, B. F. et al. Neural circuits. Labeling of active neural circuits in vivo with designed calcium integrators. Science 347, 755–760 (2015).

    Article  CAS  PubMed  Google Scholar 

  51. Akerboom, J. et al. Crystal structures of the GCaMP calcium sensor reveal the mechanism of fluorescence signal change and aid rational design. J. Biol. Chem. 284, 6455–6464 (2009). Together with Wang et al.52, this paper reports the X-ray crystal structures of GCaMP, providing some of the first mechanistic insights into the Ca2+-induced fluorescence response of a GECI.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  52. Wang, Q., Shui, B., Kotlikoff, M. I. & Sondermann, H. Structural basis for calcium sensing by GCaMP2. Structure 16, 1817–1827 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  53. Shaner, N. C. et al. Improved monomeric red, orange and yellow fluorescent proteins derived from Discosoma sp. red fluorescent protein. Nat. Biotechnol. 22, 1567–1572 (2004).

    Article  CAS  PubMed  Google Scholar 

  54. Carlson, H. J. & Campbell, R. E. Circular permutated red fluorescent proteins and calcium ion indicators based on mCherry. Protein Eng. Des. Sel. 26, 763–772 (2013).

    Article  CAS  PubMed  Google Scholar 

  55. Shaner, N. C. et al. Improving the photostability of bright monomeric orange and red fluorescent proteins. Nat. Methods 5, 545–551 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  56. Kredel, S. et al. mRuby, a bright monomeric red fluorescent protein for labeling of subcellular structures. PLoS ONE 4, e4391 (2009).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  57. Shemiakina, I. I. et al. A monomeric red fluorescent protein with low cytotoxicity. Nat. Commun. 3, 1204 (2012).

    Article  CAS  PubMed  Google Scholar 

  58. Shen, Y. et al. A genetically encoded Ca2+ indicator based on circularly permutated sea anemone red fluorescent protein eqFP578. BMC Biol. 16, 9 (2018).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  59. Abdelfattah, A. S. et al. A bright and fast red fluorescent protein voltage indicator that reports neuronal activity in organotypic brain slices. J. Neurosci. 36, 2458–2472 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  60. Dana, H. et al. Sensitive red protein calcium indicators for imaging neural activity. eLife 5, e12727 (2016).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  61. Shaner, N. C. et al. A bright monomeric green fluorescent protein derived from Branchiostoma lanceolatum. Nat. Methods 10, 407–409 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  62. Ai, H.-W. W., Henderson, J. N., Remington, S. J. & Campbell, R. E. Directed evolution of a monomeric, bright and photostable version of Clavularia cyan fluorescent protein: structural characterization and applications in fluorescence imaging. Biochem. J. 400, 531–540 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  63. Hoi, H. et al. An engineered monomeric Zoanthus sp. yellow fluorescent protein. Chem. Biol. 20, 1296–1304 (2013).

    Article  CAS  PubMed  Google Scholar 

  64. McKinney, S. A., Murphy, C. S., Hazelwood, K. L., Davidson, M. W. & Looger, L. L. A bright and photostable photoconvertible fluorescent protein. Nat. Methods 6, 131–133 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  65. Clavel, D. et al. Structural analysis of the bright monomeric yellow-green fluorescent protein mNeonGreen obtained by directed evolution. Acta Crystallogr. D Struct. Biol. 72, 1298–1307 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  66. Remington, S. J. et al. zFP538, a yellow-fluorescent protein from Zoanthus, contains a novel three-ring chromophore. Biochemistry 44, 202–212 (2005).

    Article  CAS  PubMed  Google Scholar 

  67. Zarowny, L. et al. Bright and high-performance genetically encoded Ca2+ indicator based on mNeonGreen fluorescent protein. ACS Sens. 5, 1959–1968 (2020).

    Article  CAS  PubMed  Google Scholar 

  68. Subach, O. M. et al. Novel genetically encoded bright positive calcium indicator NCaMP7 based on the mNeonGreen fluorescent protein. Int. J. Mol. Sci. 21, 1644 (2020).

    Article  CAS  PubMed Central  Google Scholar 

  69. Chen, Z. & Ai, H.-W. Single fluorescent protein-based indicators for zinc ion (Zn2+). Anal. Chem. 88, 9029–9036 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  70. Zhao, Y. et al. Inverse-response Ca2+ indicators for optogenetic visualization of neuronal inhibition. Sci. Rep. 8, 11758 (2018).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  71. Arai, S. et al. RGB-color intensiometric indicators to visualize spatiotemporal dynamics of ATP in single cells. Angew. Chem. Int. Ed. 57, 10873–10878 (2018).

    Article  CAS  Google Scholar 

  72. De Boer, M. et al. Conformational and dynamic plasticity in substrate-binding proteins underlies selective transport in ABC importers. eLife 8, e44652 (2019).

    Article  PubMed  PubMed Central  Google Scholar 

  73. Mao, B., Pear, M. R., McCammon, J. A. & Quiocho, F. A. Hinge-bending in l-arabinose-binding protein. The “Venus’s-flytrap” model. J. Biol. Chem. 257, 1131–1133 (1982).

    Article  CAS  PubMed  Google Scholar 

  74. Marvin, J. S., Schreiter, E. R., Echevarría, I. M. & Looger, L. L. A genetically encoded, high-signal-to-noise maltose sensor. Proteins 79, 3025–3036 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  75. Nadler, D. C., Morgan, S.-A., Flamholz, A., Kortright, K. E. & Savage, D. F. Rapid construction of metabolite biosensors using domain-insertion profiling. Nat. Commun. 7, 12266 (2016). This paper describes a systematic method for the discovery of single FP-based indicators through the use of transposons to create large libraries in which cpGFP is randomly inserted into the sensing domain.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  76. Mita, M. et al. Green fluorescent protein-based glucose indicators report glucose dynamics in living cells. Anal. Chem. 91, 4821–4830 (2019).

    Article  CAS  PubMed  Google Scholar 

  77. Keller, J. P. et al. In vivo glucose imaging in multiple model organisms with an engineered single-wavelength sensor. Preprint at bioRxiv https://doi.org/10.1101/571422 (2019).

  78. Alicea, I. et al. Structure of the Escherichia coli phosphonate binding protein PhnD and rationally optimized phosphonate biosensors. J. Mol. Biol. 414, 356–369 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  79. Marvin, J. S. et al. An optimized fluorescent probe for visualizing glutamate neurotransmission. Nat. Methods 10, 162–170 (2013). This paper describes the development of iGluSnFr, a single FP-based glutamate indicator based on an SBP. iGluSnFr is the archetype for the ever-expanding SnFr series of biosensors.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  80. Latorraca, N. R., Venkatakrishnan, A. J. & Dror, R. O. GPCR dynamics: structures in motion. Chem. Rev. 117, 139–155 (2017).

    Article  CAS  PubMed  Google Scholar 

  81. Chamberland, S. et al. Fast two-photon imaging of subcellular voltage dynamics in neuronal tissue with genetically encoded indicators. eLife 6, e25690 (2017).

    Article  PubMed  PubMed Central  Google Scholar 

  82. Zhao, Y., Shen, Y., Wen, Y. & Campbell, R. E. High-performance intensiometric direct- and inverse-response genetically encoded biosensors for citrate. ACS Cent. Sci. 6, 1441–1450 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  83. Shcherbakova, D. M., Stepanenko, O. V., Turoverov, K. K. & Verkhusha, V. V. Near-infrared fluorescent proteins: multiplexing and optogenetics across scales. Trends Biotechnol. 36, 1230–1243 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  84. Qian, Y. et al. A genetically encoded near-infrared fluorescent calcium ion indicator. Nat. Methods 16, 171–174 (2019).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  85. Qian, Y. et al. Improved genetically encoded near-infrared fluorescent calcium ion indicators for in vivo imaging. Preprint at bioRxiv https://doi.org/10.1101/2020.04.08.032433 (2020).

  86. Yu, D. et al. A naturally monomeric infrared fluorescent protein for protein labeling in vivo. Nat. Methods 12, 763–765 (2015).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  87. Berman, H. M. et al. The protein data bank. Nucleic Acids Res. 28, 235–242 (2000).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  88. Scheepers, G. H., Lycklama a Nijeholt, J. A. & Poolman, B. An updated structural classification of substrate-binding proteins. FEBS Lett. 590, 4393–4401 (2016).

    Article  CAS  PubMed  Google Scholar 

  89. Vongsouthi, V. et al. A computationally designed fluorescent biosensor for d-serine. Preprint at bioRxiv https://doi.org/10.1101/2020.08.18.255380 (2020).

  90. Haydon, D. J. & Guest, J. R. A new family of bacterial regulatory proteins. FEMS Microbiol. Lett. 63, 291–295 (1991).

    Article  CAS  PubMed  Google Scholar 

  91. Jain, D. Allosteric control of transcription in GntR family of transcription regulators: a structural overview. IUBMB Life 67, 556–563 (2015).

    Article  CAS  PubMed  Google Scholar 

  92. Arce-Molina, R. et al. A highly responsive pyruvate sensor reveals pathway-regulatory role of the mitochondrial pyruvate carrier MPC. eLife 9, e53917 (2020).

    Article  PubMed  PubMed Central  Google Scholar 

  93. Schiefner, A. & Skerra, A. The menagerie of human lipocalins: a natural protein scaffold for molecular recognition of physiological compounds. Acc. Chem. Res. 48, 976–985 (2015).

    Article  CAS  PubMed  Google Scholar 

  94. Lagerström, M. C. & Schiöth, H. B. Structural diversity of G protein-coupled receptors and significance for drug discovery. Nat. Rev. Drug Discov. 7, 339–357 (2008).

    Article  PubMed  CAS  Google Scholar 

  95. Shu, X., Shaner, N. C., Yarbrough, C. A., Tsien, R. Y. & Remington, S. J. Novel chromophores and buried charges control color in mFruits. Biochemistry 45, 9639–9647 (2006).

    Article  CAS  PubMed  Google Scholar 

  96. Muslinkina, L. et al. Two independent routes of post-translational chemistry in fluorescent protein FusionRed. Int. J. Biol. Macromol. 155, 551–559 (2020).

    Article  CAS  PubMed  Google Scholar 

  97. Berardozzi, R., Adam, V., Martins, A. & Bourgeois, D. Arginine 66 controls dark-state formation in green-to-red photoconvertible fluorescent proteins. J. Am. Chem. Soc. 138, 558–565 (2016).

    Article  CAS  PubMed  Google Scholar 

  98. Ding, J., Luo, A. F., Hu, L., Wang, D. & Shao, F. Structural basis of the ultrasensitive calcium indicator GCaMP6. Sci. China Life Sci. 57, 269–274 (2014).

    Article  CAS  PubMed  Google Scholar 

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Acknowledgements

We thank F. Subach, K. Horikawa, Y. Yang, T. Nagai, Y. Qin, Y. Li, F. Sun and H. Ai for providing gene sequences, and G. Baird for comments. R.E.C. acknowledges the Japan Society for the Promotion of Science (JSPS), Natural Sciences and Engineering Research Council of Canada (NSERC) and Canadian Institutes of Health Research (CIHR) for funding support.

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Y.N., Y.S. and R.E.C. wrote and edited the manuscript. Y.N., Y.S., L.K. and R.E.C. performed the literature survey that informed the conclusions and opinions expressed in this Perspective.

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Correspondence to Robert E. Campbell.

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R.E.C. is listed as an inventor on patents related to the development of various monomeric FPs. R.E.C. and Y.S. are listed as inventors on patent applications that describe single FP-based Ca2+ biosensors.

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Nasu, Y., Shen, Y., Kramer, L. et al. Structure- and mechanism-guided design of single fluorescent protein-based biosensors. Nat Chem Biol 17, 509–518 (2021). https://doi.org/10.1038/s41589-020-00718-x

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