Near-infrared genetically encoded positive calcium indicator based on GAF-FP bacterial phytochrome
Name
ijms-20-03488.pdf
Size
5.37 MB
Format
Adobe PDF
Checksum (MD5)
5cee4d7c953a1bc416c701a7157236be
Author(s)
Piatkevich, Kiryl
Date Issued
July 16, 2019
Journal
International Journal of Molecular Sciences
Publisher
Multidisciplinary Digital Publishing Institute
Citation
Subach,Oksana M., Natalia V. Barykina, Konstantin V. Anokhin, Kiryl D. Piatkevich, and Fedor V. Subach, "Near-infrared genetically encoded positive calcium indicator based on GAF-FP bacterial phytochrome." International Journal of Molecular Sciences 20, 14 (July 2019): no. 3488 doi 10.3390/ijms20143488 ©2019 Author(s)
Version
Final published version
Abstract
A variety of genetically encoded calcium indicators are currently available for visualization of calcium dynamics in cultured cells and in vivo. Only one of them, called NIR-GECO1, exhibits fluorescence in the near-infrared region of the spectrum. NIR-GECO1 is engineered based on the near-infrared fluorescent protein mIFP derived from bacterial phytochromes. However, NIR-GECO1 has an inverted response to calcium ions and its excitation spectrum is not optimal for the commonly used 640 nm lasers. Using small near-infrared bacterial phytochrome GAF-FP and calmodulin/M13-peptide pair, we developed a near-infrared calcium indicator called GAF-CaMP2. In vitro, GAF-CaMP2 showed a positive response of 78% and high affinity (Kd of 466 nM) to the calcium ions. It had excitation and emission maxima at 642 and 674 nm, respectively. GAF-CaMP2 had a 2.0-fold lower brightness, 5.5-fold faster maturation and lower pH stability compared to GAF-FP in vitro. GAF-CaMP2 showed 2.9-fold higher photostability than smURFP protein. The GAF-CaMP2 fusion with sfGFP demonstrated a ratiometric response with a dynamic range of 169% when expressed in the cytosol of mammalian cells in culture. Finally, we successfully applied the ratiometric version of GAF-CaMP2 for the simultaneous visualization of calcium transients in three organelles of mammalian cells using four-color fluorescence microscopy. Keywords: calcium imaging; genetically encoded calcium indicator; protein engineering; near-infrared fluorescent bacterial phytochrome
MIT Department
Massachusetts Institute of Technology. Media Laboratory
Terms of Use
Creative Commons Attribution
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.3390/ijms20143488
