Download MendeleyFilament-mediated repurposing of toxic dITP for immunity in the Kongming system.
Feng, H., Shao, K., Zeng, Z., Tan, E.Y.J., Hu, Z., Zhao, R., Rao, J., Shi, J., Chen, Z., Redondo, R.P., Wu, B., Han, W., Luo, M.(2026) Mol Cell 86: 1148-1163.e5
- PubMed: 41638214 Search on PubMed
- DOI: https://doi.org/10.1016/j.molcel.2026.01.027
- Primary Citation Related Structures:
8ZSF, 8ZSG, 8ZSH, 9XVC - PubMed Abstract:
Abortive infection systems protect bacteria by triggering self-destruction in response to phage attack. Most known systems rely on stable cyclic nucleotides that accumulate to stoichiometric levels to activate effectors; the Kongming (Kom) system employs the toxic metabolite deoxyinosine triphosphate (dITP) as its signaling molecule. Here, we show that the Escherichia coli KomB-KomC (KomBC) complex forms a preassembled filament that remains inactive until dITP binding induces cooperative allosteric activation. KomB, a homolog of the nucleotide-hydrolyzing enzyme HAM1, has lost catalytic activity but evolved a high-affinity, hydrolysis-resistant binding pocket for dITP. Interestingly, substoichiometric dITP binding is sufficient to activate adjacent KomC NADase domains, which propagate activation cooperatively along the filament. This filament-based architecture enables ultrasensitive, long-range allosteric signaling in response to a low-abundance and short-lived metabolite. Our findings reveal an ultrasensitive immune strategy that transforms a toxic byproduct into a robust antiviral trigger, expanding the known repertoire of bacterial defense strategies.
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore.
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