Abstract
Phage HK022 Nun protein excludes phage λ by terminating transcription near the λnutsites. We have established a purifiedin vitrosystem that reproduces thein vivosequence and factor requirements of Nun. Nun arrests transcription byE. coliRNA polymerase at or near elongation pause sites distal to thenutsites. TheboxB sequence ofnutis required for optimal Nun activity;boxA plays a lesser role. The efficiency of transcription arrest is strongly enhanced by the fourE. coliNus factors. The factors increase the specific activity of Nun, and allow it to act at higher ribonucleoside triphosphate concentrations. A wild-typeboxA is required for stimulation by Nus factors. Nun and the λ N antitermination protein compete for their opposing reactions. This competition may be at the level of binding ofboxB RNA.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
