Dimethylsulfoxide Targets Phage RNA Polymerases To Promote Transcription

Dimethylsulfoxide is a "universal" solvent in areas of pharmaceutical sciences and cell biology. Dimethylsulfoxide was previously reported to facilitate in vitro transcription of RNA from chromatin and supercoiled plasmid, with the underlying mechanism being attributed to the alteration of the template structure. Here we demonstrated that low concentrations of Dimethylsulfoxide significantly increase the phage polymerase-catalyzed RNA synthesis when the naked and short PCR products were used as templates, suggesting that Dimethylsulfoxide promotes transcription through additional mechanism(s). Interestingly, SP6 polymerase was more sensitive to the Dimethylsulfoxide stimulation than T7 polymerase, suggesting that the polymerase is an important target for Dimethylsulfoxide stimulation of RNA synthesis. Consistently, we showed that Dimethylsulfoxide dramatically elevated the RNA polymerase activity and slightly increased the affinity (K_M) with the DNA template. The elevated polymerase activity is explained by the altered polymerase structure reflected by the changed intrinsic fluorescence. Furthermore, Dimethylsulfoxide was shown to simultaneously accumulate both the abortive and full-length transcripts, leading us to conclude that the Dimethylsulfoxide-altered polymerase structure primarily encodes an enhanced activity at the stage of transcription initiation. Dimethylsulfoxide-induced alteration of the polymerase structure and function highlights a mechanism that may be general in interpreting the molecular action of this popular solvent.