Fluctuations in the initiation rate of transcription, the first step in gene expression, ensue from the stochastic behavior of the molecular process that controls transcription. In steady state, the regulatory process is often assumed to operate reversibly, i.e., in equilibrium. However, reversibility imposes fundamental limits to information processing. For instance, on the assumption of equilibrium, it is difficult to explain the precision with which the process executes its task in eukaryotes. Here we provide evidence -- from microscopic analyses of the transcription dynamics at a single gene copy of yeast -- that the regulatory process for transcription is cyclic and irreversible (out of equilibrium). The necessary coupling to reservoirs of free energy occurs via sequence-specific transcriptional activators and the recruitment, in part, of ATP-dependent chromatin remodelers. Our findings may help explain
how eukaryotic cells reconcile the dual but opposing requirements for fast regulatory kinetics and high regulatory specificity.

Raw MFM microscopy images have been sliced and registered according to z position into an image stack. Subsequently, a maximum intensity projection and background subtraction was completed using a darkfield image. Puncta were detected, intensities quantified and molecular traces were obtained. These traces are captured in this dataset. In addition, "on" and "off" states were assigned to each frame in each trace. These binerized traces are also present. 

Hinrich Boeger, Corrosponding author. hboerger@ucsc.edu.