FIG. 2.

Summary of assay results for fusion constructs present in the E. coli JH372 reporter strain. The results for each of the λcI DBD fusions we constructed and examined in the JH372 reporter strain are depicted. The extent of each segment from AbrB, Abh, and SpoVT fused to the λcI DBD is denoted numerically (e.g., 4-94 indicates fusion of amino acid residues spanning position 4 to position 94). The AbrB monomer is 94 residues in length, Abh is 92 residues, and SpoVT is 178 residues. Fused fragments containing a missense mutation are indicated by the nature of the amino acid change (one-letter code) at the residue position relative to the native, intact protein monomer (e.g., C54Y indicates a mutation changing cysteine to tyrosine at the 54th residue relative to the native monomer start point). The results of both phage immunity tests and β-galactosidase assays are given. S, sensitive to λ infection (i.e., no multimerization brought about by the fused segment); I, immune to λ infection (i.e., the fused segment can self-assemble into a multimeric state). The dimeric and tetrameric forms of the GCN4 protein fusions used as controls are described in references 15 and 33. (Figures 3, 5, and 6 present cartoons summarizing different aspects of these results along with the results shown in Fig. 4.)