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.
Fusicoccin activates KAT1 channels by stabilizing their interaction with 14-3-3 proteins / A. Saponaro, A. Porro, A. Chaves-Sanjuan, M. Nardini, O. Rauh, G. Thiel, A. Moroni. - In: PLANT CELL. - ISSN 1040-4651. - 29:10(2017), pp. 2570-2580. ((Intervento presentato al 61. convegno Biophysical Meeting tenutosi a New Orleans nel 2017.
|Titolo:||Fusicoccin activates KAT1 channels by stabilizing their interaction with 14-3-3 proteins|
SAPONARO, ANDREA COSIMO (Primo)
PORRO, ALESSANDRO (Secondo)
NARDINI, MARCO (Penultimo)
MORONI, ANNA (Ultimo) (Corresponding)
|Parole Chiave:||Plant Science; Cell Biology; KAT1 channels; 14-3-3 protein; Fusicoccin|
|Settore Scientifico Disciplinare:||Settore BIO/04 - Fisiologia Vegetale|
Settore BIO/10 - Biochimica
|Progetto:||Noninvasive Manipulation of Gating in Ion Channels|
|Data di pubblicazione:||2017|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1105/tpc.17.00375|
|Appare nelle tipologie:||01 - Articolo su periodico|