Cooperative Interaction of Transcription Termination Factors with the RNA Polymerase II C-terminal Domain

Phosphorylation of the C-terminal domain of RNA polymerase II controls the co-transcriptional assembly of RNA processing and transcription factors. Recruitment relies on conserved CTDinteracting domains that recognize different CTD phosphoisoforms during the transcription cycle, but the molecular basis for their specificity remains unclear. We show that the CTD-interacting domains of two transcription termination factors, Rtt103 and Pcf11, achieve high affinity and specificity both by specifically recognizing the phosphorylated CTD and by cooperatively binding to neighboring CTD repeats. Single amino acid mutations at the protein-protein interface abolish cooperativity and affect recruitment at the 3′-end processing site in vivo. We suggest that this cooperativity provides a signal-response mechanism to ensure that its action is confined only to proper polyadenylation sites where Serine 2 phosphorylation density is highest

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion