TY  - JOUR
U1  - Wissenschaftlicher Artikel
A1  - Saponaro, Andrea
A1  - Porro, Alessandro
A1  - Chaves-Sanjuan, Antonio
A1  - Nardini, Marco
A1  - Rauh, Oliver
A1  - Thiel, Gerhard
A1  - Moroni, Anna
T1  - Fusicoccin Activates KAT1 Channels by Stabilizing Their Interaction with 14-3-3 Proteins
JF  - The Plant Cell
N2  - 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.
Y1  - 2017
SN  - 1040-4651
SS  - 1040-4651
U6  - https://doi.org/10.1105/tpc.17.00375
DO  - https://doi.org/10.1105/tpc.17.00375
PM  - 28970335
VL  - 29
IS  - 10
SP  - 2570
EP  - 2580
S1  - 11
ER  -