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Fusicoccin Activates KAT1 Channels by Stabilizing their Interaction with 14-3-3- Proteins.

Saponaro, Andrea and Porro, Alessandro and Chaves-Sanjuan, Antonio and Nardini, Marco and Rauh, Oliver and Thiel, Gerhard and Moroni, Anna (2017):
Fusicoccin Activates KAT1 Channels by Stabilizing their Interaction with 14-3-3- Proteins.
In: The Plant cell, pp. 2570-2580, 29, (10), ISSN 1532-298X,
[Article]

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 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 co-crystallized it with tobacco 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 non-canonical binding site for the toxin that adopts a novel conformation, never described before. The structural insights underscore the adaptability of fusicoccin, predicting more potential targets than so far anticipated. The data furthermore advocate a common mechanism of regulation of the proton pump and a potassium channel, two essential elements in K+ uptake in plant cells.

Item Type: Article
Erschienen: 2017
Creators: 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.
Language: English
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 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 co-crystallized it with tobacco 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 non-canonical binding site for the toxin that adopts a novel conformation, never described before. The structural insights underscore the adaptability of fusicoccin, predicting more potential targets than so far anticipated. The data furthermore advocate a common mechanism of regulation of the proton pump and a potassium channel, two essential elements in K+ uptake in plant cells.

Journal or Publication Title: The Plant cell
Volume: 29
Number: 10
Divisions: 10 Department of Biology
10 Department of Biology > Plant Membrane Biophysics
Date Deposited: 18 Oct 2017 07:09
Identification Number: pmid:28970335
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