Mechanism of Sen1 translocation

Transcription termination is a critical step for gene regulation and genome integrity among all kingdoms of life. In <i>Saccharomyces cerevisiae</i>, one the major pathways accomplished by Sen1 helicase, homolog to human Senataxin (SETX), defection which raises diseases central nervus system human. Although it has been proposed that translocates along nucleic acids consuming adenosine triphosphates (ATPs) during termination, mechanism this translocation activity not well understood. work, our aim investigate measuring interactions between different types polyacrylamide gel electrophoresis (PAGE) assay or single-molecule Fӧrster resonance energy transfer (FRET) assay. We firstly observe unwinding on tailed duplex DNA in presence 1 mM ATP via PAGE assay, where involved. As binding crucial translocation, then we examine affinity single-stranded revealing stable with an occupied length less than 24 nt. µM ATP, dynamically binds dissociates from FRET By titrating concentrations 1–500 µM, gradual decrease mean durations binding, suggesting ATP-dependent DNA. fit these classical Michaelis-Menten model obtain minimum duration (0.18 ± 0.01) s at saturating <i>K</i><sub>m</sub> (13.1 0.1) Sen1. This result consistent Taking into account half tail, i.e. 13 nt, rate 70 nt/s estimated. Reversing direction, increase suggests impediment front possible Our quantitative measurements are helpful deepening understanding eukaryotic transcription