Plasmid-DNAgram: Anagram Solving by Molecular Interactions in Living Cells by FRET between Variants of the Green Fluorescent Protein

Plasmid-DNAgram, a variant of DNAgram, adopted the concept of DNAgram that linguistic information could be encoded on bio-molecular sequences. For example, a DNA restriction map of "BsiWI XhoI EcoRV DraI" could be regarded as a word, "word." Plasmid-DNAgram aims to do linguistic information processing in vivo. To demonstrate this purpose, we used the fused catalytic and regulatory subunits of PKA to GFP mutants with excitation and emission spectra suitable for FRET. The indication that FRET between the tagged PKA subunits occurs was obtained by co-transfecting COS-7 cells or HEK293T cells with RII-CFP and C-YFP, exciting at 458 nm, the optimum for CFP, and collecting emissions at 480 and 550 nm for CFP and YFP, respectively. CFP could be regarded as a sign of adjective, and YFP as a noun-tag. Normal expression-level of fluorescent protein means that it is carrying correct semantic information. The physiological modulation of FRET would be able to correspond with the pragmatics. In conclusion, our results indicate that imaging of FRET between variants of GFP in living cells could be considered as a simple linguistic information processing in vivo.