@article{LuDreyerDickinsonetal.2023,
  author    = {Lu, Jinping and Dreyer, Ingo and Dickinson, Miles Sasha and Panzer, Sabine and Jaślan, Dawid and Navarro-Retamal, Carlos and Geiger, Dietmar and Terpitz, Ulrich and Becker, Dirk and Stroud, Robert M. and Marten, Irene and Hedrich, Rainer},
  title     = {Vicia faba SV channel VfTPC1 is a hyperexcitable variant of plant vacuole two pore channels},
  series = {eLife},
  volume    = {12},
  journal   = {eLife},
  doi       = {10.7554/eLife.86384},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-350264},
  year      = {2023},
  abstract  = {To fire action-potential-like electrical signals, the vacuole membrane requires the two-pore channel TPC1, formerly called SV channel. The TPC1/SV channel functions as a depolarization-stimulated, non-selective cation channel that is inhibited by luminal Ca\(^{2+}\). In our search for species-dependent functional TPC1 channel variants with different luminal Ca\(^{2+}\) sensitivity, we found in total three acidic residues present in Ca\(^{2+}\) sensor sites 2 and 3 of the Ca\(^{2+}\)-sensitive AtTPC1 channel from Arabidopsis thaliana that were neutral in its Vicia faba ortholog and also in those of many other Fabaceae. When expressed in the Arabidopsis AtTPC1-loss-of-function background, wild-type VfTPC1 was hypersensitive to vacuole depolarization and only weakly sensitive to blocking luminal Ca\(^{2+}\). When AtTPC1 was mutated for these VfTPC1-homologous polymorphic residues, two neutral substitutions in Ca\(^{2+}\) sensor site 3 alone were already sufficient for the Arabidopsis At-VfTPC1 channel mutant to gain VfTPC1-like voltage and luminal Ca\(^{2+}\) sensitivity that together rendered vacuoles hyperexcitable. Thus, natural TPC1 channel variants exist in plant families which may fine-tune vacuole excitability and adapt it to environmental settings of the particular ecological niche.},
  language  = {en}
}
@article{LehmannJorgensenFratzetal.2021,
  author    = {Lehmann, Julian and J{\o}rgensen, Morten E. and Fratz, Stefanie and M{\"u}ller, Heike M. and Kusch, Jana and Scherzer, S{\"o}nke and Navarro-Retamal, Carlos and Mayer, Dominik and B{\"o}hm, Jennifer and Konrad, Kai R. and Terpitz, Ulrich and Dreyer, Ingo and Mueller, Thomas D. and Sauer, Markus and Hedrich, Rainer and Geiger, Dietmar and Maierhofer, Tobias},
  title     = {Acidosis-induced activation of anion channel SLAH3 in the flooding-related stress response of Arabidopsis},
  series = {Current Biology},
  volume    = {31},
  journal   = {Current Biology},
  doi       = {10.1016/j.cub.2021.06.018},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-363320},
  pages     = {3575-3585},
  year      = {2021},
  abstract  = {Plants, as sessile organisms, gained the ability to sense and respond to biotic and abiotic stressors to survive severe changes in their environments. The change in our climate comes with extreme dry periods but also episodes of flooding. The latter stress condition causes anaerobiosis-triggered cytosolic acidosis and impairs plant function. The molecular mechanism that enables plant cells to sense acidity and convey this signal via membrane depolarization was previously unknown. Here, we show that acidosis-induced anion efflux from Arabidopsis (Arabidopsis thaliana) roots is dependent on the S-type anion channel AtSLAH3. Heterologous expression of SLAH3 in Xenopus oocytes revealed that the anion channel is directly activated by a small, physiological drop in cytosolic pH. Acidosis-triggered activation of SLAH3 is mediated by protonation of histidine 330 and 454. Super-resolution microscopy analysis showed that the increase in cellular proton concentration switches SLAH3 from an electrically silent channel dimer into its active monomeric form. Our results show that, upon acidification, protons directly switch SLAH3 to its open configuration, bypassing kinase-dependent activation. Moreover, under flooding conditions, the stress response of Arabidopsis wild-type (WT) plants was significantly higher compared to SLAH3 loss-of-function mutants. Our genetic evidence of SLAH3 pH sensor function may guide the development of crop varieties with improved stress tolerance.},
  language  = {en}
}
@article{DeğirmenciRogeFerreiraVukosavljevicetal.2023,
  author    = {Değirmenci, Laura and Rog{\´e} Ferreira, Fabio Luiz and Vukosavljevic, Adrian and Heindl, Cornelia and Keller, Alexander and Geiger, Dietmar and Scheiner, Ricarda},
  title     = {Sugar perception in honeybees},
  series = {Frontiers in Physiology},
  volume    = {13},
  journal   = {Frontiers in Physiology},
  issn      = {1664-042X},
  doi       = {10.3389/fphys.2022.1089669},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-302284},
  year      = {2023},
  abstract  = {Honeybees (Apis mellifera) need their fine sense of taste to evaluate nectar and pollen sources. Gustatory receptors (Grs) translate taste signals into electrical responses. In vivo experiments have demonstrated collective responses of the whole Gr-set. We here disentangle the contributions of all three honeybee sugar receptors (AmGr1-3), combining CRISPR/Cas9 mediated genetic knock-out, electrophysiology and behaviour. We show an expanded sugar spectrum of the AmGr1 receptor. Mutants lacking AmGr1 have a reduced response to sucrose and glucose but not to fructose. AmGr2 solely acts as co-receptor of AmGr1 but not of AmGr3, as we show by electrophysiology and using bimolecular fluorescence complementation. Our results show for the first time that AmGr2 is indeed a functional receptor on its own. Intriguingly, AmGr2 mutants still display a wildtype-like sugar taste. AmGr3 is a specific fructose receptor and is not modulated by a co-receptor. Eliminating AmGr3 while preserving AmGr1 and AmGr2 abolishes the perception of fructose but not of sucrose. Our comprehensive study on the functions of AmGr1, AmGr2 and AmGr3 in honeybees is the first to combine investigations on sugar perception at the receptor level and simultaneously in vivo. We show that honeybees rely on two gustatory receptors to sense all relevant sugars.},
  language  = {en}
}