Phage HK022 Nun protein arrests transcription on phage lambda DNA in vitro and competes with the phage lambda N antitermination protein.
Phage HK022 Nun protein excludes phage lambda by terminating transcription near the lambda nut sites. We have established a purified in vitro system that reproduces the in vivo sequence and factor requirements of Nun. Nun arrests transcription by E. coli RNA polymerase at or near elongation pause sites distal to the nut sites. The boxB sequence of nut is required for optimal Nun activity; boxA plays a lesser role. The efficiency of transcription arrest is strongly enhanced by the four E. coli Nus factors. The factors increase the specific activity of Nun, and allow it to act at higher ribonucleoside triphosphate concentrations. A wild-type boxA is required for stimulation by Nus factors. Nun and the lambda N antitermination protein compete for their opposing reactions. This competition may be at the level of binding of boxB RNA.
Hung
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Department of Biochemistry and Molecular Biophysics, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
Gottesman
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D001426:Bacterial Proteins / Q000378:metabolism / Q000502:physiology; D010582:Bacteriophage lambda / Q000235:genetics*; D001483:Base Sequence; D001667:Binding, Competitive; D003090:Coliphages / Q000235:genetics / Q000502:physiology*; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism / Q000821:virology; D029968:Escherichia coli Proteins; D015967:Gene Expression Regulation, Viral; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D010445:Peptide Elongation Factors / Q000502:physiology; D012045:Regulatory Sequences, Nucleic Acid; D012269:Ribosomal Proteins / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors; D014762:Viral Interference / Q000502:physiology*; D014764:Viral Proteins / Q000502:physiology*
D001426:Bacterial Proteins; D004279:DNA, Viral; D029968:Escherichia coli Proteins; C073501:Nun protein, Enterobacteria phage HK022; C074952:NusB protein, E coli; C070291:NusG protein, E coli; D010445:Peptide Elongation Factors; D012269:Ribosomal Proteins; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; D014764:Viral Proteins; C068727:nusA protein, E coli; C029537:ribosomal protein S10; D012321:DNA-Directed RNA Polymerases