Structural and mechanistic study of the cysteine oxidation-mediated induction of the Escherichia coli MarR regulator

Multiple antibiotic resistance regulator (MarR) family proteins are widely conserved transcription factors that are important for regulating bacterial resistance to various stresses. Escherichia call MarR, the prototype member of this family, has recently been shown to undergo interdimer disulfide bond formation via a unique cysteine residue (Cys80) that ultimately triggered MarR's dissociation from its promoter DNA. However, these structural studies were performed with cysteine mutants while the structure of wild type MarR remains uncharacterized. Here we report the crystal structure of wild type MarR in the absence of DNA, which further revealed the roles of cysteine residues in MarR's transcriptional regulation. In addition, we developed a circularly permuted yellow fluorescent protein (cpYFP)based environmental-sensitive fluorescent reporter for in situ detection of the DNA-binding induced conformational change on MarR, which verified the induction mechanism of this prototypical MarR family protein. This strategy might potentially be applicable for monitoring local conformational change within diverse protein structures. (C) 2017 Elsevier Ltd. All rights reserved.