title: Isolation and characterization of transducing phage coding for sigma subunit of Escherichia coli RNA polymerase.
abstract: A transducing phage has been isolated with codes for the sigma subunit of Escherichia coli RNA polymerase. Transducing phage were selected from E. coli shotgun collections of HindIII or Sac I fragments cloned into Charon 25, a new bacteriophage lambda vector that is capble of forming lyosogens at high temperature. Transduction of an E. coli strain carrying a temperature-sensitive mutation in the sigma gene was used for the selection. The positions of restriction sites for Sac I, HindIII, Xho I, Bgl II, and Kpn I in the cloned bacterial DNA segments were determined. Phage containing the HindIII fragment complement both primase (dnaG) and sigma (rpoD) whereas those containing the Sac I fragment complement only sigma. Results of analyses of the proteins made both in vivo after infection of UV-irradiated cells and in vitro in a coupled transcription/translation system suggest that a Sac I site separates the promoter for sigma from the sigma structural gene. The direction of transcription of sigma was determined to be clockwise with respect to the E. coli genetic map.
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D004262:DNA Restriction Enzymes; D004274:DNA, Recombinant; D004926:Escherichia coli / Q000235:genetics*; D005796:Genes; D008040:Genetic Linkage; D008970:Molecular Weight; D009876:Operon; D010957:Plasmids; D012808:Sigma Factor / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004274:DNA, Recombinant; D012808:Sigma Factor; D014157:Transcription Factors; D004262:DNA Restriction Enzymes