title: Loss of sigma-factor of RNA polymerase of Xanthomonas campestris pv. oryzae during phage Xp10 infection.
abstract: Ten min after infection of Xanthomonas campestris pv. oryzae by phage Xp10, a sharp decrease in the activity of the host RNA polymerase was observed. Host RNA polymerase from phage-infected and uninfected cells was purified, and their properties were compared. The enzyme from uninfected cells contained four polypeptides with Mr = 155,000, 155,000, 93,000, and 37,000, respectively, and assembled with a stoichiometry of alpha 2 beta beta' sigma. The enzyme from infected cells lacked the sigma-subunit. The enzyme from uninfected cells utilized Xp10 DNA and poly[d(A-T)] as templates, the enzyme from phage-infected cells failed to transcribe Xp10 DNA, but retained the ability to transcribe poly(A-T). The regions of the Xp10 genome transcribed by the two enzymes were also investigated. The enzyme from uninfected cells transcribed the leftmost 25-30% of the Xp10 genome. The enzyme from phage-infected cells also transcribed the same region, but the enzyme activity was very low. Other properties such as (a) the response to RNA polymerase inhibitors, (b) the effect of N-ethylmaleimide, (c) the requirement of Mg2+ and Mn2+, and (d) the optimum temperature and pH of the two enzymes were very similar.
mesh_terms: D001435:Bacteriophages / Q000235:genetics* / Q000378:metabolism; D004262:DNA Restriction Enzymes; D012321:DNA-Directed RNA Polymerases / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D012808:Sigma Factor / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014974:Xanthomonas / Q000235:genetics* / Q000378:metabolism
chemical_list: D012808:Sigma Factor; D014157:Transcription Factors; D012321:DNA-Directed RNA Polymerases; D004262:DNA Restriction Enzymes