FIG 4.

Structural alignment of the McpN-LBD C_∝ chain with structural homologues. In all cases, McpN-LBD is shown in blue. (A) Alignment with a CHASE3 domain of an uncharacterized histidine kinase of Rhodopseudomonas palustris (PDB ID 3VA9), the closest structural homologue found in a DALI search (Table 1). (B) Alignment with Tar-LBD (PDB ID 1VLT). Bound aspartate (Tar) is shown in green, whereas bound nitrate (McpN) is shown in blue. (C) Alignment with the sensor domain of the NarX histidine kinase (PDB ID 3EZH). Bound nitrates overlap and are shown in blue (McpN) and orange (NarX).