TABLE 2.

Nitrogen source conditions in which regulation may be less dependent on NtrC activation, indicated by ntrC fitness > −1.5 and illustrated by the dark blue points in Fig. 2A

Conditions in which NtrC fitness is >−1.5
Condition	NtrC fitness
l-glutamine	−0.27
putrescine	−0.46
l-asparagine	−0.57
ammonium chloride	−0.66
4-aminobutyric acid	−0.86
4-guanidinobutyric acid	−1.30
l-histidine	−1.31
adenine	−1.43