Cyclic di-GMP integrates functionally divergent transcription factors into a regulation pathway for antioxidant defense

Nucleic Acids Res. 2018 Aug 21;46(14):7270-7283. doi: 10.1093/nar/gky611.

Abstract

Cyclic diguanylate monophosphate (c-di-GMP) is a global signaling molecule that modulates diverse cellular processes through its downstream receptors. However, no study has fully clarified the mechanisms by which c-di-GMP organizes functionally divergent regulators to drive the gene expression for coping with environmental stress. Here, we reported that c-di-GMP can integrate two functionally opposite receptor transcription factors, namely, LtmA and HpoR, into a pathway to regulate the antioxidant processes in Mycobacterium smegmatis. In contrast to HpoR, LtmA is an activator that positively regulates the expression of redox gene clusters and the mycobacterial H2O2 resistance. LtmA can physically interact with HpoR. A high level of c-di-GMP stimulates the positive regulation of LtmA and boosts the physical interaction between the two regulators, further enhancing the DNA-binding ability of LtmA and reducing the inhibitory activity of HpoR. Therefore, upon exposure to oxidative stress, c-di-GMP can orchestrate functionally divergent transcription factors to trigger antioxidant defense in mycobacteria. This finding presents a noteworthy example of how a bacterium remodels its transcriptional network via c-di-GMP in response to environmental stress.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antioxidants / metabolism*
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Cyclic GMP / analogs & derivatives*
  • Cyclic GMP / metabolism
  • Gene Expression Regulation, Bacterial*
  • Hydrogen Peroxide / metabolism
  • Mycobacterium smegmatis / genetics
  • Mycobacterium smegmatis / metabolism
  • Oxidants / metabolism
  • Protein Binding
  • Signal Transduction / genetics*
  • Transcription Factors / metabolism*

Substances

  • Antioxidants
  • Bacterial Proteins
  • Oxidants
  • Transcription Factors
  • bis(3',5')-cyclic diguanylic acid
  • Hydrogen Peroxide
  • Cyclic GMP