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Please use this identifier to cite or link to this item: http://dspace.utalca.cl/handle/1950/9167

Title: The pH sensor of the plant K plus uptake channel KAT1 is built from a sensory cloud rather than from single key amino acids
Authors: Gonzalez, W.
Riedelsberger, J.
Morales-Navarro, S.E.
Caballero, J.
Alzate-Morales, J.H.
Gonzalez-Nilo, F.D.
Dreyer, I.
Issue Date: Sep-2012
Publisher: WILEY-BLACKWELL, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA
Citation: FEBS JOURNAL Volume: 279 Special Issue: SI Supplement: 1 Pages: 455-455
Abstract: The uptake of potassium ions (K+) accompanied by an acidification of the apoplasm is a prerequisite for stomatal opening. The acidification (approximately 2–2.5 pH units) is perceived by voltage-gated inward potassium channels (Kin) that then can open their pores with lower energy cost. The sensory units for extracellular pH in stomatal Kin channels are proposed to be histidines exposed to the apoplasm. However, in the Arabidopsis thaliana stomatal Kin channel KAT1, mutations in the unique histidine exposed to the solvent (His267) do not affect the pH dependency. We demonstrate in the present study that His267 of the KAT1 channel cannot sense pH changes since the neighbouring residue Phe266 shifts its pKa to undetectable values through a cation–p interaction. Instead, we show that Glu240 placed in the extracellular loop between transmembrane segments S5 and S6 is involved in the extracellular acid activation mechanism. Based on structural models we propose that this region may serve as a molecular link between the pH- and the voltage-sensor. Like Glu240, several other titratable residues could contribute to the pH-sensor of KAT1, interact with each other and even connect such residues far away from the voltage-sensor with the gating machinery of the channel.
URI: http://dspace.utalca.cl/handle/1950/9167
ISSN: 1742-464X
Appears in Collections:Artículos en publicaciones ISI - Universidad de Talca

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