Crystal structure of the N-terminal domain of VqsR from Pseudomonas aeruginosa at 2.1 Å resolution

Abstract

VqsR is a quorum-sensing (QS) transcriptional regulator which controls QS systems (las, rhl and pqs) by directly downregulating the expression of qscR in Pseudomonas aeruginosa. As a member of the LuxR family of proteins, VqsR shares the common motif of a helix-turn-helix (HTH)-type DNA-binding domain at the C-terminus, while the function of its N-terminal domain remains obscure. Here, the crystal structure of the N-terminal domain of VqsR (VqsR-N; residues 1-193) was determined at a resolution of 2.1 Å. The structure is folded into a regular α-β-α sandwich topology, which is similar to the ligand-binding domain (LBD) of the LuxR-type QS receptors. Although their sequence similarity is very low, structural comparison reveals that VqsR-N has a conserved enclosed cavity which could recognize acyl-homoserine lactones (AHLs) as in other LuxR-type AHL receptors. The structure suggests that VqsR could be a potential AHL receptor.In this work, the crystal structure of the N-terminal domain of VqsR (VqsR-N) was determined at 2.1 Å resolution. Structural comparison demonstrated that VqsR-N has a similar structural fold and conserved enclosed cavity to those observed in the LuxR family of acyl-homoserine lactone (AHL) receptors. Structural analyses show that VqsR could be a potential AHL receptor.