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mRNA Interferase Bacillus cereus BC0266 Shows MazF-Like Characteristics Through Structural and Functional Study
Sung-Min Kang1, Ji Sung Koo1, Chang-Min Kim1
1The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanakgu, Seoul 08826, Korea.
Abstract:
Toxin-antitoxin (TA) systems are prevalent in bacteria and are known to regulate cellular growth in response to stress. As various functions related to TA systems have been revealed, the importance of TA systems are rapidly emerging. Here, we present the crystal structure of putative mRNA interferase BC0266 and report it as a type II toxin MazF. The MazF toxin is a ribonuclease activated upon and during stressful conditions, in which it cleaves mRNA in a sequence-specific, ribosome-independent manner. Its prolonged activity causes toxic consequences to the bacteria which, in turn, may lead to bacterial death. In this study, we conducted structural and functional investigations of Bacillus cereus MazF and present the first toxin structure in the TA system of B. cereus. Specifically, B. cereus MazF adopts a PemK-like fold and also has an RNA substrate-recognizing loop, which is clearly observed in the high-resolution structure. Key residues of B. cereus MazF involved in the catalytic activity are also proposed, and in vitro assay together with mutational studies affirm the ribonucleic activity and the active sites essential for its cellular toxicity.
Insights
This study reveals the crystal structure of Bacillus cereus MazF, a type II toxin-antitoxin system component. Understanding this mRNA interferase provides insights into bacterial stress response and potential therapeutic targets.
Area of Science:
- Microbiology
- Structural Biology
- Molecular Biology
Background:
- Toxin-antitoxin (TA) systems regulate bacterial growth under stress.
- The MazF toxin is an mRNA interferase crucial for bacterial stress response.
Purpose of the Study:
- To determine the crystal structure of Bacillus cereus MazF.
- To investigate the structural and functional characteristics of this type II toxin.
Main Methods:
- X-ray crystallography to obtain high-resolution structure.
- In vitro enzymatic assays.
- Site-directed mutagenesis studies.
Main Results:
- The crystal structure of Bacillus cereus MazF was determined, revealing a PemK-like fold.
- An RNA substrate-recognizing loop and key catalytic residues were identified.
- In vitro assays and mutational studies confirmed ribonucleic activity and essential active sites.
Conclusions:
- This is the first reported toxin structure within the Bacillus cereus TA system.
- The findings elucidate the mechanism of MazF-mediated mRNA cleavage and its role in bacterial toxicity.
- Structural insights pave the way for understanding bacterial stress responses and developing novel antimicrobials.
