Distinct amino acids in the C-linker domain of the plant K+ channel KAT2 determine its subcellular localization and activity at the plasma membrane.
(2014) Plant Physiology — Vol. 164, n° 3, p. 1415-1429 (2014)
Files
No attached file found for this publication.
Details
- Authors
- Abstract
- 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 6th 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 Shaker subunits, KAT2 and 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 2 contiguous amino acids, Val381 and Ser382, located in the C-linker C-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 which composes the first C-linker α-helix (A'-helix) located just below the pore, is a crucial determinant of KAT2 channel activity. A KAT2 C-linker/CNBD 3D model, based on animal HCN 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.
- Affiliations
Citations
Nieves-Cordones, M., Chavanieu, A., Jeanguenin, L., Alcon, C., Szponarski, W., Estaran, S., Chérel, I., Zimmermann, S., Sentenac, H., & Gaillard, I. (2014). Distinct amino acids in the C-linker domain of the plant K+ channel KAT2 determine its subcellular localization and activity at the plasma membrane. Plant Physiology, 164(3), 1415-1429. https://doi.org/10.1104/pp.113.229757 (Original work published 2014)