@article{SaponaroPorroChaves-Sanjuanetal.2017,
  author    = {Saponaro, Andrea and Porro, Alessandro and Chaves-Sanjuan, Antonio and Nardini, Marco and Rauh, Oliver and Thiel, Gerhard and Moroni, Anna},
  title     = {Fusicoccin Activates KAT1 Channels by Stabilizing Their Interaction with 14-3-3 Proteins},
  journal   = {The Plant Cell},
  volume    = {29},
  number    = {10},
  issn      = {1040-4651},
  doi       = {10.1105/tpc.17.00375},
  pages     = {2570 -- 2580},
  year      = {2017},
  abstract  = {Plants acquire potassium (K+) ions for cell growth and movement via regulated diffusion through K+ channels. Here, we present crystallographic and functional data showing that the K+ inward rectifier KAT1 (K+Arabidopsis thaliana 1) channel is regulated by 14-3-3 proteins and further modulated by the phytotoxin fusicoccin, in analogy to the H+-ATPase. We identified a 14-3-3 mode III binding site at the very C terminus of KAT1 and cocrystallized it with tobacco (Nicotiana tabacum) 14-3-3 proteins to describe the protein complex at atomic detail. Validation of this interaction by electrophysiology shows that 14-3-3 binding augments KAT1 conductance by increasing the maximal current and by positively shifting the voltage dependency of gating. Fusicoccin potentiates the 14-3-3 effect on KAT1 activity by stabilizing their interaction. Crystal structure of the ternary complex reveals a noncanonical binding site for the toxin that adopts a novel conformation. The structural insights underscore the adaptability of fusicoccin, predicting more potential targets than so far anticipated. The data further advocate a common mechanism of regulation of the proton pump and a potassium channel, two essential elements in K+ uptake in plant cells.},
  language  = {en}
}