## 3 Experimental Section
### Strains Employed
\begin{table}
\begin{tabular}{l l l} \hline
**Plasmids** & **Transformed into strain 594** & **Source/Ref.’; Hayes lab \#a** \\ \hline PcIpR-\(P\)-SPA-timm b & Replace D in P462 between \(Bam\)HI & KM, P467 \\  & and Ascl sites with \(Bam\)HI-P(\(\lambda\) bp’s & \\  & 39582-40280)-\(Ascl\) PCR fragment & \\ \hline pcIpR-\(P\)a76-timm & In-frame deletion76 codons: \(\lambda\)bp & KM, P515 \\  & 39609-39836 in pcIpR-\(P\)-timm with & \\  & Hpal, ligate & \\ \hline pcIpR-\(P\)a-timm & \(Bam\)HI-\(Cla\)I PCR fragment from & KM, P505 \\  & \(\lambda\)cl72\(\pi\) Lysate \#3a, replacing D- & \\  & CAP in P459 with \(\lambda\) bp’s 39582- & \\  & 40280 & \\ \hline pcIpR-\(O\)-timm & \(Bam\)HI-\(Cla\)I PCR fragment from & [36], CH, P465 \\  & \(\lambda\)cl857, replacing D-CAP in P459 with \(\lambda\) bp’s 38686-39582 & \\ \hline P434’pR-\(O\)-timm & Constitutive \(O\) expression; \(Bam\)HI- \(Cla\)I PCR fragment from \(\lambda\)cl857, & \\  & replacing D-CAP in P459 with \(\lambda\) & \\  & bp’s 38686-39582 & \\ \hline pcIpR-\(O\)-\(P\)-timm & \(Bam\)HI-\(Cla\)I PCR fragment from & CH, P569 \\  & \(\lambda\)cl857, replacing D-CAP in P459 & \\  & with \(\lambda\) bp’s 38686-39687 & \\ \hline pcIpR-\(O\)-\(63P\)-timm & \(Bam\)HI-\(Cla\)I PCR fragment from & CH, P566 \\  & \(\lambda\)cl857, replacing D-CAP in P459 & \\  & with \(\lambda\) bp’s 38686-39768 & \\ \hline pcIpR-\(O\)-\(P\)-timm & \(Bam\)HI-\(Cla\)I PCR fragment from & CH, P567 \\  & \(\lambda\)cl857, replacing D-CAP in P459 & \\  & with \(\lambda\) bp’s 38559-40280 & \\ \hline pcIpR-\(O\)-\(P\)-timm & \(Bam\)HI-\(Cla\)I PCR fragment from & CH, P568 \\  & \(\lambda\)cl857, replacing D-CAP in P459 & \\  & with \(\lambda\) bp’s 38546-40280 & \\ \hline pHB30 & \(\lambda\) bases 34499-34696, 36965-38103, & [31,34], SH lab, P8 \\  & 38814-40806 (see Section 3.2.) & \\ \hline \end{tabular}
\end{table} 
Table 10: _Cont._Construction of Expression Vectors for \(\lambda\) Genes, Gel Analysis of Plasmids, Insertion Localization  
The plasmids were extracted from cells using Qiagen plasmid mini preps. They were separated by agarose electrophoresis on gels made and run using 1X TBE buffer (10X = 1M Tris, 1M Boric acid, 0.02 M Na\({}_{2}\)EDTA, pH 8). The precursor plasmid pclpR was made by degrading pBR322 with _Eco_RI and _Bam_HI and purifying the large _Eco_RI-_bla_-rep/rop-_Bam_HI fragment. This was ligated with an 833 bp PCR fragment derived from \(\lambda c\)I857 DNA amplified using primers that added MfeI and _Bam_HI tags to the ends of lambda bases 37203 and 38036 to produce plasmid pclpR, where the ligation of the MfeI end to the _Eco_RI site removed both sites in the resulting construct. pclpR was digested with _Bam_HI and Sall and the large fragment of 4817 bp was separated from the 276 bp region between the _Bam_HI and Sall sites. A synthetic DNA sequence including \(\lambda\) oR/pR region, a _Bam_HI site, gene fusion D-CAP-_Cla_I-timm-_Eco_RI-Sall sequence provided by IDT, Coralville IA, was digested with _Bam_HI and Sall and the 710 bp fragment was ligated to the 4817 bp fragment to produce pclpR-D-CAP-timm [20]. This permitted positioning the AUG for the D-CAP fusion protein immediately to the right of the _Bam_HI sequence, and blended into the consensus Shine-Delgarno sequence, so that the D-fusion ofr was positioned 18 bp downstream from the mRNA start site for the \(\lambda\)_pR_ promoter (see Figure 1, [20]). The D-CAP ofr was removed from pclpR-D-CAP-timm \(\lambda\) by digestion with _Bam_HI and _Cla_I and the resulting large fragment was ligated with gene \(P\), produced by generating a _Bam_HI-_P-Cla_I PCR fragment, including the precise sequence of \(P\) (\(\lambda\) bp's 39582 - 40280) from \(\lambda c\)I857 DNA to yield pclpR-_P_-timm, where a TAA stop codon was added that immediately followed the \(P\) insertion. Plasmid pclpR-_P\({}^{\pm}\)_-39991_-timm was generated by inserting a _Bam_HI-_P\({}^{\pm}\)_-Cla_I PCR fragment made from \(\lambda c\)I72-_P\({}^{\pm}\)_-39991_ phage.