Light activation of transcription: photocaging of nucleotides for control over RNA polymerization

We describe the use of ATP caged with (7-(diethyl- amino)coumarin-4-yl)methyl (DEACM) for light- controlled in vitro transcription reactions. Polymerization is blocked when DEACM is bonded to the gamma phosphate group of the ATP mole- cule. Controlled light irradiation releases ATP and transcription is initiated. In order to provide full con- trol over the process, conditions involved in sub- strate release, nucleotide availability after release and the effect of the released coumarin in RNA polymerization were assessed in further detail. Together, our data provide the first direct evidence of control over enzymatic polymerization of nucleic acids through light. This approach may provide researchers with a unique tool for the study of bio- logical processes at a molecular level.