Genome of Bacteriophage P1

• DOI: 10.1128/jb.186.21.7032-7068.2004
• Publication Date: 2004-10-15T22:03:41Z
• Authors: Małgorzata B. Łob...; Debra J. Rose; Guy Plunkett; Marek Rusin; Arkadiusz Samojedny; Hansjörg Lehnherr; Michael B. Yarmol...; Frederick R. Blat...
• Keywords: Gene Expression Regulation, Viral; 2. Zero hunger; 0301 basic medicine; Binding Sites; Base Sequence; Molecular Sequence Data; Genome, Viral; Sequence Analysis, DNA; Viral Proteins; 03 medical and health sciences; Escherichia coli; Amino Acid Sequence; Bacteriophage P1

ABSTRACTP1 is a bacteriophage ofEscherichia coliand other enteric bacteria. It lysogenizes its hosts as a circular, low-copy-number plasmid. We have determined the complete nucleotide sequences of two strains of a P1 thermoinducible mutant, P1c1-100. The P1 genome (93,601 bp) contains at least 117 genes, of which almost two-thirds had not been sequenced previously and 49 have no homologs in other organisms. Protein-coding genes occupy 92% of the genome and are organized in 45 operons, of which four are decisive for the choice between lysis and lysogeny. Four others ensure plasmid maintenance. The majority of the remaining 37 operons are involved in lytic development. Seventeen operons are transcribed from σ70promoters directly controlled by the master phage repressor C1. Late operons are transcribed from promoters recognized by theE. coliRNA polymerase holoenzyme in the presence of the Lpa protein, the product of a C1-controlled P1 gene. Three species of P1-encoded tRNAs provide differential controls of translation, and a P1-encoded DNA methyltransferase with putative bifunctionality influences transcription, replication, and DNA packaging. The genome is particularly rich in Chi recombinogenic sites. The base content and distribution in P1 DNA indicate that replication of P1 from its plasmid origin had more impact on the base compositional asymmetries of the P1 genome than replication from the lytic origin of replication.