Calcium-Activated Protein Kinase CKL3 Reprograms Nuclear Transport During Plant Immune Response
Researchers identified how plants activate immune defenses by showing that calcium influx during pathogen recognition triggers a protein kinase called CKL3 to phosphorylate a nuclear pore protein, selectively blocking general nuclear traffic while allowing defense proteins through. This mechanism links calcium signaling from immune receptor activation to the execution of programmed cell death at infection sites. The finding explains a previously unknown step in how plants mount effective immune responses to pathogens.
A new study using proximity labeling techniques reveals that when plants detect pathogen effectors through NLR immune receptors, the resulting calcium surge activates a cascade that fundamentally alters nuclear transport selectivity. The calcium binds to a conserved site in the CKL3 protein kinase, enabling it to phosphorylate nucleoporin 58 (Nup58), a key component of nuclear pores. This phosphorylation event reprograms the nuclear pore to restrict general protein trafficking while selectively importing defense-related proteins needed for immune execution. The mechanism bridges a significant gap in understanding how calcium signaling from resistosome formation translates into the programmed cell death and pathogen resistance observed at infection sites. This work identifies CKL3 and Nup58 as central regulators of effector-triggered immunity and provides molecular detail on how plants coordinate their immune response.
Limitations & open questions
The study does not discuss whether this mechanism is conserved across different plant species, whether CKL3 has other roles in plant physiology beyond immunity, or the timeline of Nup58 phosphorylation relative to other immune signaling events. Additionally, the functional consequences of blocking general nuclear import during immune execution—such as effects on normal cellular processes—are not addressed.
What different sources said
- bioRxivCenter
Ca2+-activated CKL3 phosphorylates nucleoporin 58 to reprogram nuclear transport and execute effector-triggered immunity
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