Spr1814 of Streptococcus pneumoniae is a response regulator (RR) that belongs to the NarL/FixJ subfamily and has a four-helix helix-turn-helix DNA-binding domain. Here, the X-ray crystal structure of the full-length spr1814 in complex with a phosphate analogue beryllium fluoride (BeF3-) was determined at 2.0 angstrom. This allows for a structural comparison with the previously reported full-length unphosphorylated spr1814. The phosphorylation of conserved aspartic acid residue of N-terminal receiver domain triggers a structural perturbation at the alpha 4-beta 5-alpha 5 interface, leading to the domain reorganization of spr1814, and this is achieved by a rotational change in the C-terminal DNA-binding domain. (C) 2016 Elsevier Inc. All rights reserved.