The Copper Homeostasis Transcription Factor CopR Is Involved in H2O2 Stress in Lactobacillus plantarum CAUH2

Abstract

Transcriptional factors (TFs) play important roles in the responses to oxidative, acid, and other environmental stresses in Gram-positive bacteria, but the regulatory mechanism of TFs involved in oxidative stress remains unknown in lactic acid bacteria. In the present work, homologous overexpression strains with 43 TFs were constructed in the Lactobacillus plantarum CAUH2 parent strain. The strain overexpressing CopR displayed the highest sensitivity and a 110-fold decrease in survival rate under H2O2 challenge. The importance of CopR in the response to H2O2 stress was further confirmed by a 10.8-fold increase in the survival of a copR insertion mutant. In silico analysis of the genes flanking copR revealed putative CopR-binding “cop box” sequences in the promoter region of the adjacent gene copB encoding a Cu2+-exporting ATPase. Electrophoretic mobility shift assay (EMSA) analysis demonstrated the specific binding of CopR with copB in vitro, suggesting copB is a target gene of CopR in L. plantarum. The role of CopB involved in oxidative stress was verified by the significantly decreased survival in the copB mutant. Furthermore, a growth defect in copper-containing medium demonstrated that CopB functions as an export ATPase for copper ions. Furthermore, EMSAs revealed that CopR functions as a regulator that negatively regulates copB gene and Cu2+ serves as inducer of CopR to activate the expression of CopB in response to H2O2 stress in L. plantarum CAUH2. Our findings indicated that CopR plays an important role in enhancing oxidative resistance by regulating copB to modulate copper homeostasis.

Sponge microbiome stability during environmental acquisition of highly specific photosymbionts

“…The expression of two copper resistance genes by the photosymbiont in P. ficiformis is indicative of oxidation stress in the sponge environment. Expression of the gene copB by Lactobacillus plantarum CAUH2 improves oxidative tolerance as the encoded protein exports copper ions (Yang et al, 2017). Another gene highly expressed in photosymbiont-containing sponges, multicopper oxidase, encodes a factor that has been proposed to contribute to copper detoxification by converting Cu(I) to less toxic Cu(II) in the periplasm of Escherichia coli (Osman and Cavet, 2008).…”

Characterization of transcriptional response of Lactobacillus plantarum under acidic conditions provides insight into bacterial adaptation in fermentative environments

“…Previous research has shown that under oxidative stress, the copper export ATPase (copB) gene of L. plantarum is inactivated. This enhances its sensitivity to the oxidative stress conditions induced by H 2 O 2 and Cu + or Cu 2+ participating in essential redox reactions 32 .…”

Biomarkers and Utility of the Antioxidant Potential of Probiotic Lactobacilli and Bifidobacteria as Representatives of the Human Gut Microbiota

“…The copB (export ATPase for copper ions) and copR (inductor-transcription factor) genes are also involved in the response to OS triggered by H 2 O 2 in L. plantarum. It is assumed that these proteins are associated with the chelation of copper ions [86]. The chelating activity of lactobacilli and bifidobacteria is strain-specific [87].…”