title: Escherichia coli K-12 and B contain functional bacteriophage P2 ogr genes.
abstract: The bacteriophage P2 ogr gene encodes an essential 72-amino-acid protein which acts as a positive regulator of P2 late transcription. A P2 ogr deletion phage, which depends on the supply of Ogr protein in trans for lytic growth on Escherichia coli C, has previously been constructed. E. coli B and K-12 were found to support the growth of the ogr-defective P2 phage because of the presence of functional ogr genes located in cryptic P2-like prophages in these strains. The cryptic ogr genes were cloned and sequenced. Compared with the P2 wild-type ogr gene, the ogr genes in the B and K-12 strains are conserved, containing mostly silent base substitutions. One of the base substitutions in the K-12 ogr gene results in replacement of an alanine with valine at position 57 in the Ogr protein but does not seem to affect the function of Ogr as a transcriptional activator. The cryptic ogr genes are constitutively transcribed, apparently at a higher level than the wild-type ogr gene in a P2 lysogen.
authors.affiliation: Department of Biology, University of Oslo, Norway.
authors.forename: A
authors.initials: A
authors.lastname: Slettan
authors.forename: K
authors.initials: K
authors.lastname: Gebhardt
authors.forename: E
authors.initials: E
authors.lastname: Kristiansen
authors.forename: N K
authors.initials: NK
authors.lastname: Birkeland
authors.forename: B H
authors.initials: BH
authors.lastname: Lindqvist
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003090:Coliphages / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005814:Genes, Viral / Q000235:genetics; D008242:Lysogeny / Q000235:genetics*; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics*; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics*
chemical_list: D014157:Transcription Factors; D014764:Viral Proteins; C074897:ogr protein, Enterobacteria phage P2