Co-evolution of transcription factors and their targets depends on mode of regulation

Table 2 Presence of E. coli K12 transcription factors in close and remote relatives

TF type	In E. coli K12	Entero-absent*	Entero- present^†	Widely present^‡
All TFs	143	65 (45.5%)	65 (45.5%)	13 (9%)
		TFs that regulate ≤ 5 targets
All	71	34 (48%)	35 (49%)	2 (3%)
Activators	39	22 (56%)	16 (41%)	1 (3%)
Repressors	27	11 (41%)	15 (56%)	1 (3%)
Dual regulators	5	1 (20%)	4 (80%)	0 (0%)
		TFs that regulate >5 targets
All	72	31 (43%)	30 (42%)	11 (15%)
Activators^§	29	21 (72%)	7 (24%)	1 (4%)
Repressors^¶	22	7 (32%)	13 (59%)	2 (9%)
Dual regulators^¥	21	3 (14%)	10 (48%)	8 (38%)

*Absent from Enterobacteriaceae. ^†Present in Enterobacteriaceae but absent from other γ-proteobacteria. ^‡Present in most γ-proteobacteria. ^§TFs are included in this group if they activate more than five targets. If the same TF also represses targets (dual regulator), it is included in this group only if the number of targets it activates is more than twice the number of repressed targets, and if the number of repressed targets is not larger than five. ^¶TFs are included in this group if they repress more than five targets. If the TF is a dual regulator, it is included in this group only if the number of targets it represses is more than twice the number of activated targets, and if the number of activated targets is not larger than five. ^¥TFs are included in this group if they regulate more than five genes but cannot be assigned to the previous two groups.

ISSN: 1474-760X