A novel motif essential for SNARE interaction with the K+ channel KC1 and channel gating in Arabidopsis

Christopher Grefen, Zhonghua Chen, Annegret Honsbein, Naomi Donald, Adrian Hills, Michael R. Blatt

    Research output: Contribution to journalArticlepeer-review

    105 Citations (Scopus)

    Abstract

    The SNARE (for soluble N-ethylmaleimide-sensitive factor protein attachment protein receptor) protein SYP121 (=SYR1/ PEN1) of Arabidopsis thaliana facilitates vesicle traffic, delivering ion channels and other cargo to the plasma membrane, and contributing to plant cell expansion and defense. Recently, we reported that SYP121 also interacts directly with the K+ channel subunit KC1 and forms a tripartite complex with a second K+ channel subunit, AKT1, to control channel gating and K+ transport. Here, we report isolating a minimal sequence motif of SYP121 prerequisite for its interaction with KC1. We made use of yeast mating-based split-ubiquitin and in vivo bimolecular fluorescence complementation assays for protein- protein interaction and of expression and electrophysiological analysis. The results show that interaction of SYP121 with KC1 is associated with a novel FxRF motif uniquely situated within the first 12 residues of the SNARE sequence, that this motif is the minimal requirement for SNARE-dependent alterations in K+ channel gating when heterologously expressed, and that rescue of KC1-associated K+ current of the root epidermis in syp121 mutant Arabidopsis plants depends on expression of SNARE constructs incorporating this motif. These results establish the FxRF sequence as a previously unidentified motif required for SNARE-ion channel interactions and lead us to suggest a mechanistic framework for understanding the coordination of vesicle traffic with transmembrane ion transport.
    Original languageEnglish
    Pages (from-to)3076-3092
    Number of pages17
    JournalPlant Cell
    Volume22
    Issue number9
    DOIs
    Publication statusPublished - 2010

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