Suicidal phage-excluding anticodon nucleases: Bacteria and their viral parasites survive by incessant evolution of defensive measures and countermeasures. A case in point presents a survival cascade where phage induced neutralization of host DNA restriction turns on a translation disabling anticodon nuclease (PrrC) that has the potential to abort the infection but is counteracted phage tRNA repair proteins. A more sophisticated host anticodon nuclease (RloC) disrupts its tRNA target beyond repair but may be counteracted by a different phage antidote. RloC’s other salient feature is its regulation by an internal, DNA break responsive switch. This enables the activation of RloC’s ACNase by phages that degrade their host DNA. Whether RloC benefits its bacterial host also under genotoxic stress is an open question. We investigate the structure-function relationships and regulation of the two anticodon nucleases and explore the possible application of one of them as a means to protect useful bacteria from phage infection.
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