Table 1.

Change of the melting temperature (°C) of the VFT domains in the presence of a ligand

	VFT1	VFT2	VFT2F375E+Q461E	VFT2F317A+F375A
l-proline	0.55 ± 0.19	−0.03 ± 0.40
l-cysteine	0.83 ± 0.25	0.55 ± 0.19
l-serine	0.81 ± 0.27	0.52 ± 0.04
l-glutamate	0.68 ± 0.23	0.43 ± 0.09
l-pyroglutamate	0.35 ± 0.13	0.30 ± 0.24
Oxyded glutathione	0.07 ± 0.48	−0.03 ± 0.41
Reduced glutathione	0.26 ± 0.25	−0.01 ± 0.18
Ascorbate	0.70 ± 0.26	1.17 ± 0.43
Succinate*	0.47 ± 0.18	0.22 ± 0.04
Fumarate*	0.49 ± 0.20	0.81 ± 0.10
Formate*	0.26 ± 0.14	−0.01 ± 0.03
Lactate*	0.56 ± 0.18	0.60 ± 0.15
Sodium hydroxybutyrate*	0.48 ± 0.05	0.40 ± 0.09
Acetate*	0.44 ± 0.12	0.44 ± 0.15
Lithium acetoacetate*	0.07 ± 0.18	−0.29 ± 0.38
α-ketoglutarate*	0.72 ± 0.06	0.89 ± 0.09
Pyruvate*	0.88 ± 0.18	1.26 ± 0.27
MgSO4†	−0.90 ± 0.18	0.64 ± 0.21	−0.35 ± 0.42	1.00 ± 0.30
Nicotinate†	0.50 ± 0.21	2.31 ± 0.72	0.38 ± 0.19	5.01 ± 0.59
Isonicotinate†	0.79 ± 0.31	3.35 ± 0.83	0.53 ± 0.29	4.91 ± 0.67
6-hydroxy nicotinate†	0.69 ± 0.28	3.38 ± 0.88	0.64 ± 0.21	2.60 ± 0.39
6-chloro nicotinate†	0.06 ± 0.06	1.47 ± 0.46	0.20 ± 0.04	3.00 ± 0.38
Pyridine-2.5-dicarboxylate†	1.11 ± 0.34	4.83 ± 1.85	0.94 ± 0.17	4.78 ± 0.84
Quinaldate†	−0.36 ± 0.18	3.80 ± 0.88	−0.35 ± 0.30	11.19 ± 1.18
Benzoate†	0.14 ± 0.28	2.88 ± 1.19	0.03 ± 0.49	7.85 ± 1.20
Sodium salicylate	−0.73 ± 0.15	3.35 ± 0.72	−0.19 ± 0.30	10.61 ± 1.16
Nicotinamide	−0.44 ± 0.15	0.27 ± 0.25	−0.07 ± 0.02	0.52 ± 0.10
Imidazole	−0.19 ± 0.20	−0.13 ± 0.14	−0.55 ± 0.03	−0.30 ± 0.19
Histidine	0.77 ± 0.10	−0.13 ± 0.15	−0.10 ± 0.20	−0.05 ± 0.32

A thermal shift higher than 2 °C (in bold) is considered to be significant.

*Molecules that accumulate in the culture medium during bacterial growth. All molecules were tested at 30 mM except for 6-chloro nicotinate (16 mM) and pyridine-2.5-dicarboxylate (25 mM).

^†Negative modulators of virulence (6). In the present work, salicylate was found to modulate virulence at high concentration. The molecules tested by spectrofluorescence are shown in italics.