TABLE 2.

Thermodynamic parameters derived from the microcalorimetric titrations of HpaA and TyrR with different ligands and DNA fragments.

Sample cell ligand	Syringe ligand	K D (μM)	ΔH (kcal/Mol)
HpaAA153	4‐hydroxybenzoic acid	28.5 ± 2	−0.4 ± 0.03
TyrRA153	L‐Phe	Binding a
TyrRA153	L‐Phe + ATP	193 ± 24	−0.2 ± 0.01
TyrRA153	L‐Trp	2681 ± 670	−1.6 ± 0.5
TyrRA153	L‐Trp + ATP	K D1 = 1638 ± 157; K D2 = 2057 ± 263	ΔH 1 = −1.8 ± 0.3; ΔH 2 = −7.9 ± 1.7
TyrRA153	ATP	16.0 ± 0.7	−22.9 ± 1.5
TyrRA153	L‐Tyr	No binding
TyrRA153 + ATP	L‐Tyr + ATP	6.0 ± 0.2	−6.8 ± 0.1
TyrRA153	Wild‐type DNA b	0.193 ± 0.02	7.1 ± 0.1
TyrRA153 + L‐Tyr + ATP	Wild‐type DNA b  + L‐Tyr + ATP	0.081 ± 0.01	8.2 ± 0.2
TyrRA153 + L‐Phe	Wild‐type DNA b  + L‐Phe	0.074 ± 0.01	6.3 ± 0.1
TyrRA153 + L‐Trp	Wild‐type DNA b  + L‐Trp	0.442 ± 0.03	3.3 ± 0.1
TyrRA153	Mutant DNA b	No binding

Note: Data were analysed using the “One binding site model” of the MicroCal version of ORIGIN. The corresponding data are shown in Figures 6, 7, S4 and S8.

^a No satisfactory curve fit was obtained using models in SEDPHAT (Zhao et al., 2015) or the ORIGIN software (MicroCal). The corresponding titration curves are shown in Figure S8.

^b 26‐mer DNA fragments of the ipdc promoter containing the wild‐type and mutant TyrR box.