Table 3. List of 4-HPA atoms bound to NadR via ionic interactions and/or H-bonds.

4-HPA atom	NadR residue/atom	Distance (Å)
O2	TrpB39/NE1	2.83
O2	ArgB43/NH1	2.76
O1	ArgB43/NH1	3.84
O1	SerA9/OG	2.75
O1	TyrB115/OH	2.50
O2	Water (*Ser9/Asn11)	2.88
OH	AspB36/OD1/OD2	3.6/3.7

* Bond distance between the ligand carboxylate group and the water molecule, which in turn makes H-bond to the SerA9 and AsnA11 side chains.