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Brief Research Report ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Cell. Neurosci. | doi: 10.3389/fncel.2019.00482

Engineering photoactivatability in genetically encoded voltage and pH indicators

 Sungmoo Lee1, Yoon-Kyu Song2, 3 and  Bradley J. Baker1, 4*
  • 1Korea Institute of Science and Technology (KIST), South Korea
  • 2Graduate School of Convergence Science and Technology, Seoul National University, South Korea
  • 3Advanced Institutes of Convergence Technology, South Korea
  • 4Division of Bio-Medical Science and Technology, Korea University of Science and Technology, South Korea

Genetically-encoded indicators of neuronal activity enable the labeling of a genetically defined population of neurons to optically monitor their activities. However, researchers often find difficulties in identifying relevant signals from excessive background fluorescence. A photoactivatable version of a genetically encoded calcium indicator, sPA-GCaMP6f is a good example of circumventing such an obstacle by limiting the fluorescence to a region of interest defined by the user. Here, we apply this strategy to genetically encoded voltage (GEVI) and pH (GEPI) indicators. Three photoactivatable GEVI candidates were considered. The first one used a circularly-permuted fluorescent protein, the second design involved a Förster resonance energy transfer (FRET) pair, and the third approach employed a pH-sensitive variant of GFP, ecliptic pHluorin. The candidate with a variant of ecliptic pHluorin exhibited photoactivation and a voltage-dependent fluorescence change. This effort also yielded a pH-sensitive photoactivatable GFP that varies its brightness in response to intracellular pH changes.

Keywords: Voltage Imaging, Photoactivatable, GEVI, PH sensor, ecliptic pHluorin, PA-GFP, PA-Bongwoori-R3, PA-ecliptic pHluorin

Received: 14 Aug 2019; Accepted: 10 Oct 2019.

Copyright: © 2019 Lee, Song and Baker. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Mx. Bradley J. Baker, Korea Institute of Science and Technology (KIST), Bongdong-eup, South Korea, bradley.baker19@gmail.com