Download MendeleyStructural analyses of the MazEF4 toxin-antitoxin pair in Mycobacterium tuberculosis provide evidence for a unique extracellular death factor.
Ahn, D.H., Lee, K.Y., Lee, S.J., Park, S.J., Yoon, H.J., Kim, S.J., Lee, B.J.(2017) J Biol Chem 292: 18832-18847
- PubMed: 28972145
- DOI: https://doi.org/10.1074/jbc.M117.807974
- Primary Citation of Related Structures:
5XE2, 5XE3 - PubMed Abstract:
The bacterial toxin-antitoxin MazEF system in the tuberculosis (TB)-causing bacterium Mycobacterium tuberculosis is activated under unfavorable conditions, including starvation, antibiotic exposure, and oxidative stress. This system contains the ribonucleolytic enzyme MazF and has emerged as a promising drug target for TB treatments targeting the latent stage of M. tuberculosis infection and reportedly mediates a cell death process via a peptide called extracellular death factor (EDF). Although it is well established that the increase in EDF-mediated toxicity of MazF drives a cell-killing phenomenon, the molecular details are poorly understood. Moreover, the divergence in sequences among reported EDFs suggests that each bacterial species has a unique EDF. To address these open questions, we report here the structures of MazF4 and MazEF4 complexes from M. tuberculosis , representing the first MazEF structures from this organism. We found that MazF4 possesses a negatively charged MazE4-binding pocket in contrast to the positively charged MazE-binding pockets in homologous MazEF complex structures from other bacteria. Moreover, using NMR spectroscopy and biochemical assays, we unraveled the molecular interactions of MazF4 with its RNA substrate and with a new EDF homolog originating from M. tuberculosis The EDF homolog discovered here possesses a positively charged residue at the C terminus, making this EDF distinct from previously reported EDFs. Overall, our results suggest that M. tuberculosis evolved a unique MazF and EDF and that the distinctive EDF sequence could serve as a starting point for designing new anti-tuberculosis drugs. We therefore conclude that this study might contribute to the development of a new line of anti-tuberculosis agents.
Organizational Affiliation:
From the Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-gu, Seoul 151-742.
