FIG 4.

A. baumannii OxyR contains a conserved cysteine residue that is important for function. (A) Phylogenetic tree based on protein sequence alignment of A. baumannii and Acinetobacter baylyi OxyR with experimentally characterized OxyR proteins in other Gram-negative organisms. Branch lengths are representative of sequence divergence. (B) Amino acid sequence alignment for a portion of the substrate-binding domain of OxyR that contains conserved cysteine residues. An asterisk indicates complete conservation; one dot indicates similar residues at a particular position; and two dots indicate highly similar residues at a particular position. Boxed amino acid positions contain a cysteine in the A. baumannii OxyR sequence. (C) Growth of WT A. baumannii with an empty vector, the ΔoxyR strain with an empty vector, the ΔoxyR strain expressing WT oxyR in trans, or the ΔoxyR strain expressing oxyR C202S in trans in 30 µM H₂O₂. The growth curves are from a single experiment performed in biological triplicate and are representative of the results of three independent experiments.