Strains used in this work.

aAll strains were derived from Salmonella enterica serovar Typhimurium strains LT2 [49] or ATCC14028s [50]. Most mutant alleles were constructed by the λ Red method [41]–[43]. The complete list of the oligonucleotides used as PCR primers is in Table S1.
bSquare brackets following a prophage name define the genotype of that prophage. The term “scar” denotes the DNA sequence left following excision of the antibiotic-resistance cassette. Superscript indicates the plasmid used as DNA template in amplifying the cassette. For further details on phage gene nomenclature, see legend to Figure 1A. The aph and aadA genes confer resistance to kanamycin and spectinomycin, respectively. The Δ(araBAD)::xxx constructs place the gene of interest under the control of the chromosomal PBAD promoter. din-243::MudJ and din-1001::MudJ denote lacZ transcriptional fusions (generated by transposition) to the tail operon of the Gifsy-2 prophage [22] and to the Q gene of the Fels-1 prophage (N. Figueroa-Bossi, unpublished data), respectively.
cWhere not specified, the source of the strain is this work. Strains TT17217 and TT23381 were a gift of John Roth.