## 3 Results
### CII Complementation  
The assay for CII complementation, Figure 3, measures the expression and ability of plasmid cloned _cII_ to stimulate, in trans, repressor establishment transcription from promoter _pE_ encoded on two infecting heterolimume _innm_434 lambdoid phages mutated for _cII_ (clI68, 38498: T-A, Trp to Arg; cII2002, 38430: T-C, Leu to Pro). Each hybrid phage includes the WT \(\lambda\) sequence rightward from \(\lambda\) base 38265 left of _cII_, including an identical IHF binding site, RBS for _cII_, the \(-10\) and \(-35\) sequences of _pE_ and reported regions of extended dyad symmetry [50]. CII-stimulated, _pE_-dependent CI\({}_{434}\) repressor establishment transcription from the infecting phage genome confers a high level of _cl_-434-repressor expression. The CI\({}_{434}\) can bind to the _imm_434 _oL_ and _oR_ operators on the infecting phage. This blocks phage transcription from the _imm_434 _pR_ promoter, lytic phage replication and growth and arrests plaque formation at 37 \({}^{\circ}\)C or 39 \({}^{\circ}\)C, effectively shunting the infecting _cII_-defective phage into a non-vegetative (pre-lysogenic) state. Even weak _cII_ expression from [cII] at 37 \({}^{\circ}\)C was sufficient to prevent plaque formation by the infecting _imm_434 phages (Figure 3). Clear plaque forming units (pfu) arose in cell lawns incubated at 30 \({}^{\circ}\)C due to the repression of _cII_ expression from [cII]. Plasmids deleted in _cII_ for five or ten COOH-terminal amino acids (respectively cII\({}_{1-92}\) and cII\({}_{1-87}\)), or those with _cII_ mutations cII-3638, cII-3639 and cII-3638 + 3639 fully complemented for CII activation \begin{table}
\begin{tabular}{c c c c} \hline \multirow{2}{*}{**Induction Time (min)**} & \multicolumn{3}{c}{**Culture up-Shift from 30 \({}^{\circ}\)C \(\pm\) SE \({}^{\mathrm{a}}\)**} \\ \cline{2-4}  & **37 \({}^{\circ}\)C** & **39 \({}^{\circ}\)C** & **42 \({}^{\circ}\)C** \\ \hline
0 & 0 (0.2) & 0 (4.0) & 3.2 (0.05) \\
20 & 0 (0.2) & 1.4 (2.6) & 153.8 (0.5) \\
40 & 0 (0.3) & 6.7 (2.0) & 415.4 (0.4) \\
60 & 0.8 (0.3) & 23.2 (3.2) & 518.5 (0.5) \\
90 & 0 (0.3) & 41.3 (0.3) & 624.6 (0.4) \\
120 & 7.3 (14.9) & 30.0 (2.9) & 721.2 (0.4) \\
150 & 10.8 (1.3) & 84.3 (3.4) & 808.4 (0.4) \\
180 & 23.9 (2.6) & 136.9 (10.7) & 1039.5 (0.7) \\ \hline \end{tabular}
\end{table} 
Table 1: Temperature dependence of thermally inducible intra-cellular D-GFP fusion expression from plasmid pclpR-D-GFP-timm [fluorescence units (\(\pm\)SE\()\times 10^{-3}\)]. of repressor establishment transcription from \(pE\) (Table 2, Figure S2). Plasmid cII\({}_{1-77}\) and those with larger terminal deletions failed to complement for CII activity. Thus, either the last 20 amino acids, or those 11 to 20 from the C-terminal end are required for CII activation of transcription from \(pE\). Contrary to an expectation that plaque formation would be inhibited, _hftA_ cells with plasmids [cII], [cII\({}_{1-92}\)] and [cII\({}_{1-87}\)] allowed weak activation of transcription from \(pE\) but did not block phage growth, Table 2, Figure S2. Plasmid [cII\({}_{1-77}\)] was fully defective for CII complementation in _hftA_::kan cells as clear pfu were formed at 37-39 \({}^{\circ}\)C, Table 2. Significantly, the _pcnB_::kan mutation, shown to be a null allele for _pcnB_[51], completely abrogated CII complementation activity at 37 and 39 \({}^{\circ}\)C (Table 2, Figure S2). These results strongly implicate an involvement of poly (A) polymerase I in CII _complementation_ that was not noted previously. Cells with transduced rifampicin-resistant mutations in _rpoB_, encoding the \(\beta\)-subunit of \(E\). _coli_ RNA polymerase, were examined to determine if a CII-RpoB interaction was involved in CII complementation, cell toxicity, or plasmid loss.