Identification of stress-related proteins in Escherichia coli using the pollutant cis-dichloroethylene.

ABSTRACT

AIMS: To complement our proteome study, whole-transcriptome analyses were utilized here to identify proteins related to degrading cis-1,2-dichloroethylene (cis-DCE). METHODS AND RESULTS: Metabolically engineered Escherichia coli strains were utilized expressing an evolved toluene ortho-monooxygenase along with either (i) glutathione S-transferase and altered gamma-glutamylcysteine synthetase or (ii) a rationally engineered epoxide hydrolase. cis-DCE degradation induced 30 known stress genes and 32 uncharacterized genes. Because of the reactive cis-DCE epoxides formed, we hypothesized that some of these uncharacterized genes may be related to a variety of stresses. Using isogenic mutants, IbpB, YchH, YdeI, YeaR, YgiW, YoaG and YodD were related to hydrogen peroxide, cadmium and acid stress. Additional whole-transcriptome studies with hydrogen peroxide stress using the most hydrogen peroxide-sensitive mutants, ygiW and ychH, identified that FliS, GalS, HcaR, MglA, SufE, SufS, Tap, TnaB, YhcN and YjaA are also involved in the stress response of E. coli to hydrogen peroxide, cadmium and acid, as well as are involved in biofilm formation. CONCLUSION: Seventeen proteins are involved in the stress network for this organism, and YhcN and YchH were shown to be important for the degradation of cis-DCE. SIGNIFICANCE AND IMPACT OF THE STUDY Six previously uncharacterized proteins (YchH, YdeI, YgiW, YhcN, YjaA and YodD) were shown to be stress proteins.