Microbes are known to withstand environmental stresses by using chromosomal toxin–antitoxin systems. MazEF is one of the most extensively studied toxin–antitoxin systems. In stressful environments, MazF toxins modulate translation by cleaving single-stranded RNAs in a sequence-specific fashion. Previously, a chromosomal gene located at DR0417 in Deinococcus radiodurans was predicted to code for a MazF endoribonuclease (MazFDR 0417); however, its function remains unclear. In the present study, we characterized the molecular function of MazFDR 0417. Analysis of MazFDR 0417-cleaved RNA sites using modified massively parallel sequencing revealed a unique 4-nt motif, UACA, as a potential cleavage pattern. The activity of MazFDR 0417 was also assessed in a real-time fluorometric assay, which revealed that MazFDR 0417 strictly recognizes the unique tetrad UACA. This sequence specificity may allow D. radiodurans to alter its translation profile and survive under stressful conditions.
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