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Gamillus

a.k.a. GFP with acid tolerance and monomeric properties to illuminate soured environments

Gamillus is a photoswitchable green fluorescent protein published in 2018, derived from Olindias formosus. It is reported to be a very rapidly-maturing monomer with very low acid sensitivity.
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Aggregation Organism Molecular Weight Cofactor
Monomer Olindias formosus 26.5 kDa -

Attributes

State Ex λ Em λ EC (M-1 cm-1) QY Brightness pKa Maturation (min) Lifetime (ns)
Off              
On 504 519 83,000 0.9 74.7 3.4 8.0  

Transitions

From To Switch λ
Off On 388
On Off 488

Photostability

State t1/2 (s) Power Light Mode In Cell Fusion ˚C Reference
On 73.2 3.7 (W/cm2) Arc-lamp Widefield 37.0 Shinoda et al. (2018)

Gamillus Sequence

Gamillus was derived from Gamillus0.5 with the following mutations: M1_A2insVSKGEE/A150_G152delinsPHGP/K180T/E226_V232delinsGMDELYK

MVSKGEEASGRALFQYPMTSKIELNGEINGKKFKVAGEGFTPSSGRFNMHAYCTTGDLPMSWVVIASPLQYGFHMFAHYPEDITHFFQECFPGSYTLDRTLRMEGDGTLTTHHEYSLEDGCVTSKTTLNASGFDPKGATMTKSFVKQLPNEVKITPHGPNGIRLTSTVLYLKEDGTIQIGTQDCIVTPVGGRKVTQPKAHFLHTQIIQKKDPNDTRDHIVQTELAVAGNLWHGMDELYK
GenBank: BBC28144
IPG: 174808012

Structure

Deposited: ,
Chromophore:

Excerpts

Gamillus expressed in HeLa cells also exhibited a photochromic decrease in fluorescence to ∼60% or ∼10% of its initial intensity by exciting with 457–487 nm (GFP excitation range, 470 mW/cm2 for 40 s) or 488–512 nm (YFP excitation range, 360 mW/cm2 for 40 s) mercury arc light, respectively. The decreased intensity was recovered by subsequent irradiation with 352–388 nm light (770 mW/cm2 for 10 s). In contrast, such time-dependent fluorescence intensity changes were negligible using 440–480 nm excitation light as it presumably renders photochromic equilibrium of Gamillus dominant in the ionic state.

Shinoda et al. (2018)

One of the possible reasons for the negligible photochromism is a much higher on-switching rate, compared with the switching-off rate. In our estimation, the switching-on rate is ~200-fold higher than switching-off with 405 nm and 488 nm laser illumination, at the same power density... To simplify imaging we therefore selected 440–480 nm illumination to limit the photochromic phenomena. Under this excitation wavelength range, the in vitro brightness of Gamillus (calculated as the product of averaged extinction coefficients over 440–480 nm [ɛ440-480] and quantum yield) is 98% of that of EGFP (ɛ440-480 for Gamillus and EGFP were 28.8 and 35.4 mM−1 cm−1, respectively)

Shinoda et al. (2018)

Primary Reference

Acid-Tolerant Monomeric GFP from Olindias formosa

Shinoda H, Ma Y, Nakashima R, Sakurai K, Matsuda T, Nagai T

(2018). Cell Chemical Biology, 25(3) , 330-338.e7. doi: 10.1016/j.chembiol.2017.12.005. Article   Pubmed

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