Abstract
The bacterial toxin-antitoxin (TA) system regulates cell growth under various environmental stresses. Mycobacterium tuberculosis, the causative pathogen of tuberculosis (TB), has three HigBA type II TA systems with reverse gene organization, consisting of the toxin protein HigB and labile antitoxin protein HigA. Most type II TA modules are transcriptionally autoregulated by the antitoxin itself. In this report, we first present the crystal structure of the M. tuberculosis HigA3 antitoxin (MtHigA3) and MtHigA3 bound to its operator DNA complex. We also investigated the interaction between MtHigA3 and DNA using NMR spectroscopy. The MtHigA3 antitoxin structure is a homodimer that contains a structurally well conserved DNA-binding domain at the N-terminus and a dimerization domain at the C-terminus. Upon comparing the HigA homologue structures, a distinct difference was found in the C-terminal region that possesses the β-lid, and diverse orientations of two helix-turn-helix (HTH) motifs from HigA homologue dimers were observed. The structure of MtHigA3 bound to DNA reveals that the promoter DNA is bound to two HTH motifs of the MtHigA3 dimer presenting 46.5° bending, and the distance between the two HTH motifs of each MtHigA3 monomer was increased in MtHigA3 bound to DNA. The β-lid, which is found only in the tertiary structure of MtHigA3 among the HigA homologues, causes the formation of a tight dimerization network and leads to a unique arrangement for dimer formation that is related to the curvature of the bound DNA. This work could contribute to the understanding of the HigBA system of M. tuberculosis at the atomic level and may contribute to the development of new antibiotics for TB treatment.
Highlights
Tuberculosis (TB) is one of the major infectious diseases caused by the human pathogenic bacterium Mycobacterium tuberculosis, affecting 23% of the global population (Lonnroth & Raviglione, 2008)
We tried to crystallize M. tuberculosis HigA3 antitoxin (MtHigA3) with the full sequence (MALDI–TOF MS confirmed the molecular weight of purified MtHigA3 to be 12.85 kDa, which corresponds to the molecular weight of full-length MtHigA3, see Fig. S1 of the supporting information), the N-terminal residues (1 to 33 or 35) were not defined due to the missing electron density
Tuberculosis caused by M. tuberculosis is a prevalent disease worldwide, and unsuccessful treatment resulting from antibiotic resistance and tolerance of M. tuberculosis is a risk factor for global public health care
Summary
Tuberculosis (TB) is one of the major infectious diseases caused by the human pathogenic bacterium Mycobacterium tuberculosis, affecting 23% of the global population (Lonnroth & Raviglione, 2008). It is one of the top ten risk factors for death and the leading cause of death from a single infectious agent (above HIV/AIDS). The WHO estimated that 10 million people were infected with TB in 2017, among which 5– 15% of this population developed active TB, resulting in a mortality rate of 1.3 million people worldwide in a single year (WHO 2017 data; WHO, 2018). The emergence of multidrug-resistant TB (MDR-TB), which is the cause of TB treatment failure, has been a public health crisis for the last decade. In 2017, approximately 450 000 people developed MDR-TB, and the treatment success rate for MDR-TB was
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
