The Nun protein of bacteriophage HK022 inhibits translocation of Escherichia coli RNA polymerase without abolishing its catalytic activities.
Bacteriophage HK022 Nun protein blocks transcription elongation by Escherichia coli RNA polymerase in vitro without dissociating the transcription complex. Nun is active on complexes located at any template site tested. Ultimately, only the 3'-OH terminal nucleotide of the nascent transcript in an arrested complex can turn over; it is removed by pyrophosphate and restored with NTPs. This suggests that Nun inhibits the translocation of RNA polymerase without abolishing its catalytic activities. Unlike spontaneously arrested complexes, Nun-arrested complexes cannot be reactivated by transcription factor GreB. The various complexes show distinct patterns of nucleotide incorporation and pyrophosphorolysis before or after treatment with Nun, suggesting that the configuration of RNAP, transcript, and template DNA is different in each complex.
Hung
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Department of Biochemistry and Molecular Biophysics, Columbia University College of Physicians and Surgeons, New York, New York 10032 USA.
Gottesman
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D010582:Bacteriophage lambda / Q000378:metabolism*; D002384:Catalysis; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D011756:Diphosphates / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000821:virology; D029968:Escherichia coli Proteins; D007700:Kinetics; D010445:Peptide Elongation Factors / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012265:Ribonucleotides / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors; D014764:Viral Proteins / Q000378:metabolism*
D011756:Diphosphates; D029968:Escherichia coli Proteins; C079667:GreB protein, E coli; C073501:Nun protein, Enterobacteria phage HK022; D010445:Peptide Elongation Factors; D012265:Ribonucleotides; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; D014764:Viral Proteins; D012321:DNA-Directed RNA Polymerases