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The MarR-type repressor MhqR (YkvE) regulates multiple dioxygenases/glyoxalases and an azoreductase which confer resistance to 2-methylhydroquinone and catechol in Bacillus subtilis

Authors

  • Stefanie Töwe,

    1. Institute for Microbiology, Ernst-Moritz-Arndt-University of Greifswald, F.-L.-Jahn-Str. 15, D-17487 Greifswald, Germany.
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    • These authors contributed equally to this work.

  • Montira Leelakriangsak,

    1. Department of Environmental and Biomolecular Systems, OGI School of Science and Engineering, Oregon Health and Science University, Beaverton, OR 97006, USA.
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    • These authors contributed equally to this work.

  • Kazuo Kobayashi,

    1. Graduate School of Information Science, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara 630-0192, Japan.
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  • Nguyen Van Duy,

    1. Institute for Microbiology, Ernst-Moritz-Arndt-University of Greifswald, F.-L.-Jahn-Str. 15, D-17487 Greifswald, Germany.
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  • Michael Hecker,

    1. Institute for Microbiology, Ernst-Moritz-Arndt-University of Greifswald, F.-L.-Jahn-Str. 15, D-17487 Greifswald, Germany.
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  • Peter Zuber,

    1. Department of Environmental and Biomolecular Systems, OGI School of Science and Engineering, Oregon Health and Science University, Beaverton, OR 97006, USA.
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  • Haike Antelmann

    Corresponding author
    1. Institute for Microbiology, Ernst-Moritz-Arndt-University of Greifswald, F.-L.-Jahn-Str. 15, D-17487 Greifswald, Germany.
      *E-mail antelman@uni-greifswald.de; Tel. (+49) 3834 864237; Fax (+49) 3834 864202.
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*E-mail antelman@uni-greifswald.de; Tel. (+49) 3834 864237; Fax (+49) 3834 864202.

Summary

Catechol and 2-methylhydroquinone (2-MHQ) cause the induction of the thiol-specific stress response and four dioxygenases/glyoxalases in Bacillus subtilis. Using transcription factor arrays, the MarR-type regulator YkvE was identified as a repressor of the dioxygenase/glyoxalase-encoding mhqE gene. Transcriptional and proteome analyses of the ΔykvE mutant revealed the upregulation of ykcA (mhqA), ydfNOP (mhqNOP), yodED (mhqED) and yvaB (azoR2) encoding multiple dioxygenases/glyoxalases, oxidoreductases and an azoreductase. Primer extension experiments identified σA-type promoter sequences upstream of mhqA, mhqNOP, mhqED and azoR2 from which transcription is elevated after thiol stress. DNase I footprinting analysis showed that YkvE protects a primary imperfect inverted repeat with the consensus sequence of tATCTcgaAtTCgAGATaaaa in the azoR2, mhqE and mhqN promoter regions. Analysis of mhqE-promoter–bgaB fusions confirmed the significance of YkvE binding to this operator in vivo. Adjacent secondary repeats were protected by YkvE in the azoR2 and mhqN promoter regions consistent with multiple DNA–protein binding complexes. DNA-binding activity of YkvE was not directly affected by thiol-reactive compounds in vitro. Mutational analyses showed that MhqA, MhqO and AzoR2 confer resistance to 2-MHQ. Moreover, the ΔykvE mutant displayed a 2-MHQ and catechol resistant phenotype. YkvE was renamed as MhqR controlling a 2-MHQ and catechol-resistance regulon of B. subtilis.

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