title: Structural insights into the redox-switch mechanism of the MarR/DUF24-type regulator HypR.
abstract: Bacillus subtilis encodes redox-sensing MarR-type regulators of the OhrR and DUF24-families that sense organic hydroperoxides, diamide, quinones or aldehydes via thiol-based redox-switches. In this article, we characterize the novel redox-sensing MarR/DUF24-family regulator HypR (YybR) that is activated by disulphide stress caused by diamide and NaOCl in B. subtilis. HypR controls positively a flavin oxidoreductase HypO that confers protection against NaOCl stress. The conserved N-terminal Cys14 residue of HypR has a lower pK(a) of 6.36 and is essential for activation of hypO transcription by disulphide stress. HypR resembles a 2-Cys-type regulator that is activated by Cys14-Cys49' intersubunit disulphide formation. The crystal structures of reduced and oxidized HypR proteins were resolved revealing structural changes of HypR upon oxidation. In reduced HypR a hydrogen-bonding network stabilizes the reactive Cys14 thiolate that is 8-9 Å apart from Cys49'. HypR oxidation breaks these H-bonds, reorients the monomers and moves the major groove recognition α4 and α4' helices ∼4 Å towards each other. This is the first crystal structure of a redox-sensing MarR/DUF24 family protein in bacteria that is activated by NaOCl stress. Since hypochloric acid is released by activated macrophages, related HypR-like regulators could function to protect pathogens against the host immune defense.
authors.affiliation: Institute for Biochemistry, Ernst-Moritz-Arndt-University of Greifswald, D-17487 Greifswald, Germany.
authors.forename: Gottfried J
authors.initials: GJ
authors.lastname: Palm
authors.forename: Bui
authors.initials: B
authors.lastname: Khanh Chi
authors.forename: Paul
authors.initials: P
authors.lastname: Waack
authors.forename: Katrin
authors.initials: K
authors.lastname: Gronau
authors.forename: Dörte
authors.initials: D
authors.lastname: Becher
authors.forename: Dirk
authors.initials: D
authors.lastname: Albrecht
authors.forename: Winfried
authors.initials: W
authors.lastname: Hinrichs
authors.forename: Randy J
authors.initials: RJ
authors.lastname: Read
authors.forename: Haike
authors.initials: H
authors.lastname: Antelmann
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001483:Base Sequence; D003545:Cysteine / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism; D003958:Diamide / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009601:Nitroreductases / Q000235:genetics; D009875:Operator Regions, Genetic; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000096:biosynthesis / Q000235:genetics; D012973:Sodium Hypochlorite / Q000494:pharmacology; D013312:Stress, Physiological / Q000235:genetics; D015534:Trans-Activators / Q000737:chemistry* / Q000378:metabolism; D015533:Transcriptional Activation
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D015534:Trans-Activators; D003958:Diamide; D012973:Sodium Hypochlorite; D010088:Oxidoreductases; D009601:Nitroreductases; D003545:Cysteine