Cyclic nucleotide-gatedion channels(CNGCs)are key components in pattern-triggeredimmunity(PTl)signaling.Tight control of CNGC homeostasis is crucial for maintaining a balance between plant growth and immunity.Neverthe...Cyclic nucleotide-gatedion channels(CNGCs)are key components in pattern-triggeredimmunity(PTl)signaling.Tight control of CNGC homeostasis is crucial for maintaining a balance between plant growth and immunity.Nevertheless,the mechanisms for fine-tuning CNGC homeostasis remain largely unknown.Here,we report that Arabidopsis thaliana CNGC3 is a functionalcalcium channel to mediate patterninduced Ca2+influx,PTl,and resistance to Sclerotinia sclerotiorum.We identified a CNGC interactor,Skp1-interacting protein 31(SKIP31).In the absence of a pathogen,SKIP31ubiquitinates CNGC3 at Lys8 and Lys33 of the K-X-V-R motif for degradation to repress plant immunity.When a pathogen attacks,activated receptor-like cytoplasmic kinase(RLCK)BOTRYTIS-INDUCED KINASE1(BIK1)phosphorylates SKIP31 to inhibit its ubiquitin ligase activity and interaction with the CNGC3 N-terminal region,thereby suppressing CNGC3 protein degradation to promote immunity.Phosphorylation within the F box of SKlP31 at Ser88 and Ser93 and at the C-terminal Ser261 prevents its interaction with Skp1 and CNGC3,respectively.These phosphorylation sites are conserved in SKlP31 of different plant species,and SKlP31 interacts with all examined CNGCs,suggesting a pivotal role of SKIP31 phosphorylation in regulating CNGC stability and plant immunity.Moreover,biochemical assays revealed that BIK1 directly phosphorylates the CNGC3 cytoplasmic C-terminal region at four Ser residues to enhance its Ca²+channel activity,demonstrating dual roles of BlK1 in both promoting CNGC channel activity and stabilizing the channel protein.Collectively,our work unveils an SCF ubiquitin ligase-RLCK control system that fine-tunes the homeostasis of CNGCs for orchestrating plant immunity.展开更多
基金supported by grants from the Zhejiang Province Core Technology Innovation Project in Agriculture,the Hainan Provincial Natural Science Foundation of China(324CXTD430)the National Natural Science Foundation of China(31871947)the Zhejiang Provincial Natural Science Foundation of China(LZ18C140002).
文摘Cyclic nucleotide-gatedion channels(CNGCs)are key components in pattern-triggeredimmunity(PTl)signaling.Tight control of CNGC homeostasis is crucial for maintaining a balance between plant growth and immunity.Nevertheless,the mechanisms for fine-tuning CNGC homeostasis remain largely unknown.Here,we report that Arabidopsis thaliana CNGC3 is a functionalcalcium channel to mediate patterninduced Ca2+influx,PTl,and resistance to Sclerotinia sclerotiorum.We identified a CNGC interactor,Skp1-interacting protein 31(SKIP31).In the absence of a pathogen,SKIP31ubiquitinates CNGC3 at Lys8 and Lys33 of the K-X-V-R motif for degradation to repress plant immunity.When a pathogen attacks,activated receptor-like cytoplasmic kinase(RLCK)BOTRYTIS-INDUCED KINASE1(BIK1)phosphorylates SKIP31 to inhibit its ubiquitin ligase activity and interaction with the CNGC3 N-terminal region,thereby suppressing CNGC3 protein degradation to promote immunity.Phosphorylation within the F box of SKlP31 at Ser88 and Ser93 and at the C-terminal Ser261 prevents its interaction with Skp1 and CNGC3,respectively.These phosphorylation sites are conserved in SKlP31 of different plant species,and SKlP31 interacts with all examined CNGCs,suggesting a pivotal role of SKIP31 phosphorylation in regulating CNGC stability and plant immunity.Moreover,biochemical assays revealed that BIK1 directly phosphorylates the CNGC3 cytoplasmic C-terminal region at four Ser residues to enhance its Ca²+channel activity,demonstrating dual roles of BlK1 in both promoting CNGC channel activity and stabilizing the channel protein.Collectively,our work unveils an SCF ubiquitin ligase-RLCK control system that fine-tunes the homeostasis of CNGCs for orchestrating plant immunity.
