@article{GonzalezRiedelsbergerMoralesNavarroetal.2012,
  author    = {Gonzalez, Wendy and Riedelsberger, Janin and Morales-Navarro, Samuel E. and Caballero, Julio and Alzate-Morales, Jans H. and Gonzalez-Nilo, Fernando D. and Dreyer, Ingo},
  title     = {The pH sensor of the plant K+-uptake channel KAT1 is built from a sensory cloud rather than from single key amino acids},
  series = {The biochemical journal},
  volume    = {442},
  journal   = {The biochemical journal},
  number    = {7},
  publisher = {Portland Press},
  address   = {London},
  issn      = {0264-6021},
  doi       = {10.1042/BJ20111498},
  pages     = {57 -- 63},
  year      = {2012},
  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 (K-in) that then can open their pores with lower energy cost. The sensory units for extracellular pH in stomatal K-in channels are proposed to be histidines exposed to the apoplasm. However, in the Arabidopsis thaliana stomatal K-in channel KAT1, mutations in the unique histidine exposed to the solvent (His(267)) do not affect the pH dependency. We demonstrate in the present study that His(267) of the KAT1 channel cannot sense pH changes since the neighbouring residue Phe(266) shifts its pK(a) to undetectable values through a cation-pi interaction. Instead, we show that Glu(240) 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 Glu(240), 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.},
  language  = {en}
}
@misc{SharmaDreyerRiedelsberger2013,
  author    = {Sharma, Tripti and Dreyer, Ingo and Riedelsberger, Janin},
  title     = {The role of K+ channels in uptake and redistribution of potassium in the model plant Arabidopsis thaliana},
  series = {Frontiers in plant science},
  volume    = {4},
  journal   = {Frontiers in plant science},
  publisher = {Frontiers Research Foundation},
  address   = {Lausanne},
  issn      = {1664-462X},
  doi       = {10.3389/fpls.2013.00224},
  pages     = {16},
  year      = {2013},
  abstract  = {Potassium (K+) is inevitable for plant growth and development. It plays a crucial role in the regulation of enzyme activities, in adjusting the electrical membrane potential and the cellular turgor, in regulating cellular homeostasis and in the stabilization of protein synthesis. Uptake of K+ from the soil and its transport to growing organs is essential for a healthy plant development. Uptake and allocation of K+ are performed by K+ channels and transporters belonging to different protein families. In this review we summarize the knowledge on the versatile physiological roles of plant K+ channels and their behavior under stress conditions in the model plant Arabidopsis thaliana.},
  language  = {en}
}