title: Host gene expression changes and DNA amplification during temperate phage induction.
abstract: Salmonella enterica serovar Typhimurium LT2 harbors four temperate prophages. The lytic cycle of these phages was induced with hydrogen peroxide or mitomycin C. Microarray analysis was used to monitor the increase in phage genome copy number and the changes in RNA expression. Phage gene transcription was classified temporally, and host genes that responded to hydrogen peroxide, mitomycin C, or phage induction were also identified. A region of the serovar Typhimurium LT2 host genome encompassing hundreds of genes, flanking the Fels-1 lambdoid prophage, was amplified manyfold during lytic induction, presumably due to Fels-1 runoff replication prior to excision, a phenomenon termed escape replication. An excisionase (xis) mutant of Fels-1 also induced escape replication but did not get packaged. Gifsy-1, a lambdoid prophage that does not normally produce escape replication, did so after deletion of either its integrase or excisionase genes. Escape replication is probably widespread; large regions of host genome amplification were also observed after phage induction in serovar Typhimurium strains SL1344 and 14028s at the suspected integration site of prophage genomes.
authors.affiliation: Sidney Kimmel Cancer Center, 10835 Altman Row, San Diego, CA 92121, USA.
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Frye
authors.forename: Steffen
authors.initials: S
authors.lastname: Porwollik
authors.forename: Felisa
authors.initials: F
authors.lastname: Blackmer
authors.forename: Pui
authors.initials: P
authors.lastname: Cheng
authors.forename: Michael
authors.initials: M
authors.lastname: McClelland
mesh_terms: D004254:DNA Nucleotidyltransferases / Q000235:genetics / Q000502:physiology; D004261:DNA Replication; D004269:DNA, Bacterial / Q000378:metabolism; D020536:Enzyme Activators / Q000494:pharmacology; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005814:Genes, Viral; D006861:Hydrogen Peroxide / Q000494:pharmacology; D019426:Integrases / Q000235:genetics / Q000502:physiology; D016685:Mitomycin / Q000494:pharmacology; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D039002:Prophages / Q000235:genetics / Q000502:physiology*; D012483:Salmonella Phages / Q000235:genetics / Q000502:physiology*; D012486:Salmonella typhimurium / Q000235:genetics / Q000502:physiology / Q000821:virology*; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology; D014775:Virus Activation / Q000187:drug effects; D019065:Virus Assembly; D014779:Virus Replication
chemical_list: D004269:DNA, Bacterial; D020536:Enzyme Activators; D014764:Viral Proteins; D016685:Mitomycin; D006861:Hydrogen Peroxide; D004254:DNA Nucleotidyltransferases; D019426:Integrases; C063911:excisionase