Fig. 1

Superposition of FNT channel structures. (a) Superposition of experimentally determined structures of formate (PDB ID: 3KCU; monomer B;), nitrite (PDB ID: 4FC4; monomer A;) and hydrosulphide (PDB ID: 3TDR; monomer I;) channel structures. Only the backbone of six transmembrane helical segments and the Ω- and S-loops were considered for superposition. Side-chains and the loops connecting the transmembrane segments are not shown for clarity. (b) Superposition of functionally important Ω- and S-loops from five different monomers from three formate channel structures. Monomer A from PDB ID: 3KCU, monomers A and E from PDB ID: 3KLY and monomers A and B from PDB ID: 3Q7K were superposed in the same way as described in Fig. 1A. Only the backbone of the two loop regions is displayed to illustrate the conformational changes of Ω-loop. Molecules plotted in this figure and subsequent figures utilized the VMD software package [72]. Thr-91 from the Ω-loop and His-209 from the S-loop are shown in stick representation. It should be noted that Thr-91 has moved away representing the open state of FNT structure [26]