Structure Report for: 3PI6

Bahl, C.D., Madden, D.R.

Title: Pseudomonas aeruginosa Cif defines a distinct class of alpha/beta epoxide hydrolases utilizing a His/Tyr ring-opening pair
Bahl CD, Madden DR
Ref: Protein Pept Lett, 19:186, 2012 : PubMed
Abstract


ESTHER: Bahl_2012_Protein.Pept.Lett_19_186
PubMedSearch: Bahl 2012 Protein.Pept.Lett 19 186
PubMedID: 21933119
Gene_locus related to this paper: pseae-PA2934

Abstract

The Gram-negative bacterium Pseudomonas aeruginosa is an opportunistic pathogen that secretes a multitude of virulence factors during the course of infection. Among these is Cif, an epoxide hydrolase (EH) that reduces the functional localization of the cystic fibrosis transmembrane conductance regulator in epithelial cells. In addition to being the first reported EH virulence factor, Cif possesses unique sequence deviations from canonical EH motifs. Foremost among these is the substitution of a histidine for the first epoxide ring-opening tyrosine in the active site. To test the functional equivalence of Tyr and His side chains at this position, we have generated the mutant Cif-H177Y. Structural analysis confirms that both the WT His and mutant Tyr side chains can be accommodated without large-scale conformational changes. However, the Tyr mutant is functionally inactive. Based on a detailed analysis of the structure of the Tyr mutant, it appears that Cif's main-chain conformation imposes a functional requirement for a His at this position. Comparison with canonical EH structures reveals additional conformational differences, which are coupled to divergent sequence characteristics. When used to probe the genomes of other opportunistic pathogens, these sequence-structure criteria uncover candidate sequences that appear to form a distinct subfamily of Cif-like epoxide hydrolases characterized by a conserved His/Tyr ring-opening pair.