Selection of RNA-Cleaving TNA Enzymes for Cellular Mg2+ Imaging

Catalytic DNA-based fluorescent sensors have enabled cellular imaging of metal ions such as Mg2+. However, natural DNA is prone to nuclease-mediated degradation. Here, we report the in vitro selection of threose nucleic acid enzymes (TNAzymes) with RNA endonuclease activities. One such TNAzyme, T17-22, catalyzes a site-specific RNA cleavage reaction with a k(cat) of 0.017 min(-1) and K-M of 675 nM. A fluorescent sensor based on T17-22 responds to an increasing concentration of Mg2+ with a limit of detection at 0.35 mM. This TNAzyme-based sensor also allows cellular imaging of Mg2+. This work presents the first proof-of-concept demonstration of using a TNA catalyst in cellular metal ion imaging.

Automated summary

This study reports the selection of TNAzymes with RNA endonuclease activities through in vitro selection. One of the TNAzymes, T17-22, catalyzes site-specific RNA cleavage with a k(cat) of 0.017 min(-1) and K-M of 675 nM. A fluorescent sensor based on T17-22 responds to increasing concentrations of Mg2+ with a detection limit of 0.35 mM. This TNAzyme-based sensor enables cellular imaging of Mg2+. This work provides the first proof-of-concept demonstration of using a TNA catalyst in cellular metal ion imaging.