Calcium-Activated Protein Kinase CKL3 Reprograms Nuclear Transport During Plant Immune Response
Researchers have identified a molecular pathway linking calcium influx to nuclear transport reprogramming during plant immune responses, showing that the kinase CKL3 phosphorylates a nuclear pore component called Nup58 to selectively control which proteins enter the nucleus during infection. This mechanism operates downstream of resistosome formation — a key step in effector-triggered immunity (ETI) — and helps explain how plants execute programmed cell death at infection sites to halt pathogen spread. The findings fill a major gap in understanding how plants translate pathogen recognition into coordinated immune execution at the nuclear level.
When plants recognize pathogen-derived effector molecules via NLR receptors, they activate effector-triggered immunity (ETI), which involves resistosome formation, sustained cytosolic calcium influx, and ultimately programmed cell death at infection sites. Until now, the molecular steps connecting calcium signaling to immune execution remained poorly understood. Using TurboID proximity labeling centered on the nuclear pore component nucleoporin 58 (Nup58), the researchers found that ETI does not broadly disrupt nuclear trafficking; instead, it restricts general nuclear import while selectively enhancing the nuclear entry of defense-related proteins. This selective reprogramming is driven by elevated cytosolic calcium binding to a conserved residue (Asp-149) in the kinase CASEIN KINASE 1-LIKE 3 (CKL3), which then interacts with and phosphorylates Nup58 at Ser-149, altering nuclear pore selectivity. The study thus establishes CKL3 and Nup58 as central regulators bridging calcium signaling to nuclear transport changes and immune execution in plants.
What's missing
The study is a preprint posted on bioRxiv and has not yet undergone formal peer review, so findings should be treated as preliminary. Key open questions include whether CKL3-Nup58 phosphorylation is sufficient on its own to drive immune execution or requires additional co-factors, how broadly this mechanism is conserved across plant species beyond the model system studied, and whether pathogens have evolved counter-strategies targeting this pathway. The structural basis by which Nup58 phosphorylation at Ser-149 alters pore selectivity for specific cargo proteins also remains to be resolved.
What different sources said
- bioRxivCenter
Ca2+-activated CKL3 phosphorylates nucleoporin 58 to reprogram nuclear transport and execute effector-triggered immunity
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