6XU4

Crystal structure of the genetically-encoded FGCaMP calcium indicator in its calcium-bound state

Summary for 6XU4

• Entry DOI: 10.2210/pdb6xu4/pdb
• Descriptor: FGCamp, CALCIUM ION (3 entities in total)
• Functional Keywords: fgcamp, calcium sensor, calcium indicator, genetically encoded, troponin, florescent protein, fluorescent protein
• Biological source: Aspergillus niger
• Total number of polymer chains: 3
• Total formula weight: 140871.16

Authors

Boyko, K.M.,Nikolaeva, A.Y.,Korzhenevskiy, D.A.,Barykina, N.V.,Subach, O.M.,Subach, F.V. (deposition date: 2020-01-17, release date: 2020-04-15, Last modification date: 2024-11-13)

Primary citation

Barykina, N.V.,Sotskov, V.P.,Gruzdeva, A.M.,Wu, Y.K.,Portugues, R.,Subach, O.M.,Chefanova, E.S.,Plusnin, V.V.,Ivashkina, O.I.,Anokhin, K.V.,Vlaskina, A.V.,Korzhenevskiy, D.A.,Nikolaeva, A.Y.,Boyko, K.M.,Rakitina, T.V.,Varizhuk, A.M.,Pozmogova, G.E.,Subach, F.V.
FGCaMP7, an Improved Version of Fungi-Based Ratiometric Calcium Indicator for In Vivo Visualization of Neuronal Activity.
Int J Mol Sci, 21:-, 2020

PubMed Abstract: Genetically encoded calcium indicators (GECIs) have become a widespread tool for the visualization of neuronal activity. As compared to popular GCaMP GECIs, the FGCaMP indicator benefits from calmodulin and M13-peptide from the fungi and , which prevent its interaction with the intracellular environment. However, FGCaMP exhibits a two-phase fluorescence behavior with the variation of calcium ion concentration, has moderate sensitivity in neurons (as compared to the GCaMP6s indicator), and has not been fully characterized in vitro and in vivo. To address these limitations, we developed an enhanced version of FGCaMP, called FGCaMP7. FGCaMP7 preserves the ratiometric phenotype of FGCaMP, with a 3.1-fold larger ratiometric dynamic range in vitro. FGCaMP7 demonstrates 2.7- and 8.7-fold greater photostability compared to mEGFP and mTagBFP2 fluorescent proteins in vitro, respectively. The ratiometric response of FGCaMP7 is 1.6- and 1.4-fold higher, compared to the intensiometric response of GCaMP6s, in non-stimulated and stimulated neuronal cultures, respectively. We reveal the inertness of FGCaMP7 to the intracellular environment of HeLa cells using its truncated version with a deleted M13-like peptide; in contrast to the similarly truncated variant of GCaMP6s. We characterize the crystal structure of the parental FGCaMP indicator. Finally, we test the in vivo performance of FGCaMP7 in mouse brain using a two-photon microscope and an NVista miniscope; and in zebrafish using two-color ratiometric confocal imaging.

PubMed: 32344594
DOI: 10.3390/ijms21083012

Experimental method

X-RAY DIFFRACTION (3.18 Å)