TABLE 2.

Domain 4 similarities^a

Domain 4	E-value for similarity to domain 4 of:
	E. coli σE	Phage 7-11 σ	E. coli σ70
B. subtilis σW	2e−15	2e−4	No alignment
E. coli σE		No alignment	0.42
Phage 7-11 σ			No alignment

^aPairwise alignment of σ₄ domains predicted in protein sequences of phage ECF (7-11 and phiEco32), bacterial ECF (σ^E and σ^W), and group I (E. coli RpoD) σ factors. For the phiEco32 σ factor, the entire ECF domain was used in the analysis.