5NWK

14-3-3c in complex with CPP and fusicoccin

Summary for 5NWK

• Entry DOI: 10.2210/pdb5nwk/pdb
• Descriptor: 14-3-3 c-1 protein, Potassium channel KAT1, FUSICOCCIN, ... (5 entities in total)
• Functional Keywords: potassium channel, fusicoccin, complex, 14-3-3m, signaling protein
• Biological source: Nicotiana tabacum (Common tobacco); More
• Cellular location: Membrane; Multi-pass membrane protein: Q39128
• Total number of polymer chains: 16
• Total formula weight: 246956.78

Authors

Saponaro, A.,Porro, A.,Chaves-Sanjuan, A.,Nardini, M.,Thiel, G.,Moroni, A. (deposition date: 2017-05-06, release date: 2017-11-22, Last modification date: 2024-01-17)

Primary citation

Saponaro, A.,Porro, A.,Chaves-Sanjuan, A.,Nardini, M.,Rauh, O.,Thiel, G.,Moroni, A.
Fusicoccin Activates KAT1 Channels by Stabilizing Their Interaction with 14-3-3 Proteins.
Plant Cell, 29:2570-2580, 2017

PubMed 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 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 () 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.

PubMed: 28970335
DOI: 10.1105/tpc.17.00375

Experimental method

X-RAY DIFFRACTION (3.3 Å)