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Nature Is Weird  /  microbiology

A protein designed to organize and protect bacterial DNA has been weaponized into a toxin that shatters the genetic structure of rival cells.

Bacteria usually use the ParB-CTPase protein to neatly fold and segregate their own chromosomes during growth. Certain pathogens have evolved a modified version of this protein that acts as a lethal toxin during close-range combat with other microbes. This hijacked protein enters a target cell and triggers a massive collapse of its entire DNA architecture. It represents a shocking case of biological recycling where a fundamental component of life becomes a precise instrument of death. Understanding this conversion reveals how bacteria turn their own essential machinery into weapons against plants and animals. This discovery provides a roadmap for designing antimicrobial tools that trick pathogens into destroying their own genetic code.

Original Paper

Repurposing a chromosome segregation ParB-CTPase fold into an ATPase toxin for contact-dependent growth inhibition in plant and animal pathogens

Kaljevic, J.; Mundy, J. E. A.; Stojilkovic, B.; Rejzek, M.; Oms, T.; Goormaghtigh, F.; McLean, T. C.; Tran, N. T.; Johnson, K. E.; Medeiros, A. S.; Sourjik, V.; Eltschkner, S.; Melderen, L. v.; Hocher, A.; Le, T. B. K.

bioRxiv  ·  10.64898/2026.05.05.722872

Bacterial competition drives the evolution of antibacterial mechanisms, yet how new activities arise remains poorly understood. A major route to innovation is the reuse of pre-existing genetic systems, whereby conserved protein modules are repurposed in new biological contexts to generate new capabilities. Here, we show that the ParB-CTPase fold, a conserved nucleotide-binding module best known for its role in chromosome segregation, can be functionally repurposed as an antibacterial toxin. We i