title: The bacteriophage lambda O replication protein: isolation and characterization of the amplified initiator.
abstract: The bacteriophage lambda O protein participates in the initiation of lambda DNA replication. The lambda O gene was cloned into plasmid pKC30 such that its expression was controlled by the lambda PL promoter. A lambda prophage-coded thermosensitive cI repressor was used to regulate transcription of the cloned O gene. Thermal inactivation of the lambda cI repressor resulted in overproduction of the O protein until it constituted approximately 20% of the total cellular protein of Escherichia coli. A simple three-step purification protocol was developed that yields several milligrams of homogeneous O protein per gram of cell paste. The precise position of the O gene in the known lambda DNA sequence was identified from the amino-terminal sequence of the isolated O protein. Purified O protein stimulated the replication of plasmid lambda dv DNA in vitro and specifically bound to duplex DNA fragments carrying the lambda replication origin.
mesh_terms: D000595:Amino Acid Sequence; D010582:Bacteriophage lambda / Q000235:genetics*; D001483:Base Sequence; D004261:DNA Replication; D004262:DNA Restriction Enzymes; D004926:Escherichia coli / Q000235:genetics*; D005784:Gene Amplification; D005796:Genes; D005814:Genes, Viral; D006358:Hot Temperature; D010957:Plasmids; D014176:Protein Biosynthesis; D014764:Viral Proteins / Q000235:genetics / Q000302:isolation & purification*; D014779:Virus Replication
chemical_list: D014764:Viral Proteins; D004262:DNA Restriction Enzymes