Dynamical Phases and Noise in Transcription Process

Transcription, the process of polymerization of mRNA is catalyzed by a molecular machine, RNA polymerase. It uses DNA template as a track on which it moves like a motor utilizing chemical energy supplied by NTP hydrolysis.  It has been observed experimentally that many RNAPs simultaneously move on the same track (very similar to one way traffic on the road).  We give a model which takes into account steric interactions among the RNAPs as well as the mechanochemical cycle of the RNAPs. We plot three dimensional phase diagrams of the RNAP traffic using extremum current hypothesis for our model.  Recent in-vivo experiments with single cells show that the transcription process takes place into bursts. In another model we include switching of the gene between on and off state, together with mechanochemical cycle and steric interactions. This model accounts for statistical properties of transcriptional bursts.