Abstract
Rhodopsins had long been considered non-fluorescent until a peculiar voltage-sensitive fluorescence was reported for archaerhodopsin-3 (Arch3) derivatives. These proteins named QuasArs have been used for imaging membrane voltage changes in cell cultures and small animals, but they could not be applied in living rodents. To develop the next generation of sensors, it is indispensable to first understand the molecular basis of the fluorescence and its modulation by the membrane voltage. Based on spectroscopic studies of fluorescent Arch3 derivatives, we propose a unique photo-reaction scheme with extended excited-state lifetimes and inefficient photoisomerization. Molecular dynamics simulations of Arch3, of the Arch3 fluorescent derivative Archon1, and of several its mutants have revealed different voltage-dependent changes of the hydrogen-bonding networks including the protonated retinal Schiff-base and adjacent residues. Experimental observations suggest that under negative voltage, these changes modulate retinal Schiff base deprotonation and promote a decrease in the populations of fluorescent species. Finally, we identified molecular constraints that further improve fluorescence quantum yield and voltage sensitivity.
| Original language | English |
|---|---|
| Article number | 5501 |
| Pages (from-to) | 1-20 |
| Number of pages | 20 |
| Journal | Nature Communications |
| Volume | 13 |
| DOIs | |
| Publication status | Published - 20 Sept 2022 |
Bibliographical note
Funding Information:We thank, S. Augustin, J. Brandhorst, J. Schäfers, M. Meiworm, and C. Schnick for technical assistance. We thank Martin Heck and Joel Kaufmann for their assistance with HPLC measurements. This work was funded by Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany´s Excellence Strategy—EXC 2008/1–390540038 “Unifying Systems in Catalysis” (A.S., P.He., S.H., H.S., and T.U.) and SFB1078—221545957, sub-project A2 (U.A.), and SFB1449—431232613, sub-project A04 (U.A.). We thank the European Community—Access to Research Infrastructures action of the Improving Human Potential Program “LaserLab Europe” (RII-CT-2003-506350) for travel grants and financial support to perform ultrafast pump-probe experiments (A.S. and P.He.). Y.H., P.E.K., and J.T.M.K were supported by the Netherlands Organization for Scientific Research (NWO) through a VICI grant to J.T.M.K. R.F. and P.H. are grateful for funding from the Hector Fellow Academy (30000619, Peter Hegemann). P.He. is a Hertie Professor for Biophysics and Neuroscience and is supported by the Hertie Foundation. S.H., H.S., and T.U. thank the North-German Supercomputing Alliance (HLRN) and Adam Lange for providing us with computational time.
Publisher Copyright:
© 2022, The Author(s).
Funding
We thank, S. Augustin, J. Brandhorst, J. Schäfers, M. Meiworm, and C. Schnick for technical assistance. We thank Martin Heck and Joel Kaufmann for their assistance with HPLC measurements. This work was funded by Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany´s Excellence Strategy—EXC 2008/1–390540038 “Unifying Systems in Catalysis” (A.S., P.He., S.H., H.S., and T.U.) and SFB1078—221545957, sub-project A2 (U.A.), and SFB1449—431232613, sub-project A04 (U.A.). We thank the European Community—Access to Research Infrastructures action of the Improving Human Potential Program “LaserLab Europe” (RII-CT-2003-506350) for travel grants and financial support to perform ultrafast pump-probe experiments (A.S. and P.He.). Y.H., P.E.K., and J.T.M.K were supported by the Netherlands Organization for Scientific Research (NWO) through a VICI grant to J.T.M.K. R.F. and P.H. are grateful for funding from the Hector Fellow Academy (30000619, Peter Hegemann). P.He. is a Hertie Professor for Biophysics and Neuroscience and is supported by the Hertie Foundation. S.H., H.S., and T.U. thank the North-German Supercomputing Alliance (HLRN) and Adam Lange for providing us with computational time.
| Funders | Funder number |
|---|---|
| Hertie Foundation | |
| European Commission | RII-CT-2003-506350 |
| European Commission | |
| Deutsche Forschungsgemeinschaft | EXC 2008/1–390540038, SFB1449—431232613, SFB1078—221545957 |
| Deutsche Forschungsgemeinschaft | |
| Nederlandse Organisatie voor Wetenschappelijk Onderzoek | |
| Hector Fellow Academy | 30000619 |
| Hector Fellow Academy |