TldR: TnpB’s evolutionary shift from transposon nucleases to RNA-guided transcriptional regulators

TnpB proteins are transposon-encoded nucleases involved in transposon DNA propagation. Wiegand et al. identified a new class of TnpB-derived proteins, called TnpB-like nuclease-dead repressors (TldRs), which function as RNA-guided transcriptional regulators targeting conserved promoter regions. In Enterobacteriaceae, bacteriophages use TldRs and an adjacent phage gene to modulate host flagellar assembly.