Distinct Amino Acids in the C-Linker Domain of the Arabidopsis K+ Channel KAT2 Determine Its Subcellular Localization and Activity at the Plasma Membrane. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Plant Physiology Année : 2014

Distinct Amino Acids in the C-Linker Domain of the Arabidopsis K+ Channel KAT2 Determine Its Subcellular Localization and Activity at the Plasma Membrane.

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.

Dates et versions

hal-00962147 , version 1 (20-03-2014)

Identifiants

Citer

Manuel Nieves-Cordones, Alain Chavanieu, Linda Jeanguenin, Carine Alcon, Wojciech Szponarski, et al.. Distinct Amino Acids in the C-Linker Domain of the Arabidopsis K+ Channel KAT2 Determine Its Subcellular Localization and Activity at the Plasma Membrane.. Plant Physiology, 2014, 164 (3), pp.1415-29. ⟨10.1104/pp.113.229757⟩. ⟨hal-00962147⟩
138 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More