ESTARAN Sebastien
Thème de Recherche: Chimie des Acides Aminés, Peptides, Hétérocycles, Chimie Sup
sebastien.estaran
umontpellier.fr
0448792070
Bureau: N2G18, Etg: 2 - Site : Pôle Chimie Balard Recherche
Domaines de Recherche: - Sciences du Vivant/Biologie végétale
|
Productions scientifiques :
|
|
Distinct Amino Acids in the C-Linker Domain of the Arabidopsis K+ Channel KAT2 Determine Its Subcellular Localization and Activity at the Plasma Membrane.
Auteur(s): Nieves-Cordones Manuel, Chavanieu A., Jeanguenin Linda, Alcon Carine, Szponarski Wojciech, Estaran S., Chérel Isabelle, Zimmermann Sabine, Sentenac Hervé, Gaillard Isabelle
(Article) Publié:
Plant Physiology, vol. 164 p.1415-29 (2014)
Ref HAL: hal-00962147_v1
PMID 24406792
DOI: 10.1104/pp.113.229757
Résumé: Shaker K(+) channels form the major K(+) conductance of the plasma membrane in plants. They are composed of four subunits arranged around a central ion-conducting pore. The intracellular carboxy-terminal region of each subunit contains several regulatory elements, including a C-linker region and a cyclic nucleotide-binding domain (CNBD). The C-linker is the first domain present downstream of the sixth transmembrane segment and connects the CNBD to the transmembrane core. With the aim of identifying the role of the C-linker in the Shaker channel properties, we performed subdomain swapping between the C-linker of two Arabidopsis (Arabidopsis thaliana) Shaker subunits, K(+) channel in Arabidopsis thaliana2 (KAT2) and Arabidopsis thaliana K(+) rectifying channel1 (AtKC1). These two subunits contribute to K(+) transport in planta by forming heteromeric channels with other Shaker subunits. However, they display contrasting behavior when expressed in tobacco mesophyll protoplasts: KAT2 forms homotetrameric channels active at the plasma membrane, whereas AtKC1 is retained in the endoplasmic reticulum when expressed alone. The resulting chimeric/mutated constructs were analyzed for subcellular localization and functionally characterized. We identified two contiguous amino acids, valine-381 and serine-382, located in the C-linker carboxy-terminal end, which prevent KAT2 surface expression when mutated into the equivalent residues from AtKC1. Moreover, we demonstrated that the nine-amino acid stretch 312TVRAASEFA320 that composes the first C-linker α-helix located just below the pore is a crucial determinant of KAT2 channel activity. A KAT2 C-linker/CNBD three-dimensional model, based on animal HCN (for Hyperpolarization-activated, cyclic nucleotide-gated K(+)) channels as structure templates, has been built and used to discuss the role of the C-linker in plant Shaker inward channel structure and function.
|