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Structural insights into the redox-switch mechanism of the MarR/DUF24-type regulator HypR.

Published version
Peer-reviewed

Type

Article

Change log

Authors

Palm, Gottfried J 
Khanh Chi, Bui 
Waack, Paul 
Gronau, Katrin 
Becher, Dörte 

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.

Description

Keywords

Bacillus subtilis, Bacterial Proteins, Base Sequence, Cysteine, DNA-Binding Proteins, Diamide, Gene Expression Regulation, Bacterial, Models, Molecular, Molecular Sequence Data, Nitroreductases, Operator Regions, Genetic, Oxidation-Reduction, Oxidoreductases, Sodium Hypochlorite, Stress, Physiological, Trans-Activators, Transcriptional Activation

Journal Title

Nucleic Acids Res

Conference Name

Journal ISSN

0305-1048
1362-4962

Volume Title

40

Publisher

Oxford University Press (OUP)
Sponsorship
Wellcome Trust (082961/Z/07/Z)