%0 Journal Article %1 RN1083 %A Mumm, P. %A Imes, D. %A Martinoia, E. %A Al-Rasheid, K. A. S. %A Geiger, D. %A Marten, I. %A Hedrich, R. %D 2013 %J Molecular Plant %K c-terminal deactivation myOwn %N 5 %P 1550-1563 %R 10.1093/mp/sst008 %T C-Terminus-Mediated Voltage Gating of Guard Cell Anion Channel QUAC1 %U /brokenurl#<Go to ISI>://WOS:000324829400014 %V 6 %X Here, we compared the highly voltage- and malate-dependent gating kinetics of R-/QUAC-type currents of guard cell protoplasts with QUAC1 expressed in oocytes. Truncations and mutation of QUAC1 indicated that the C-terminus is involved in the voltage-dependent gating mechanism of QUAC1.Anion transporters in plants play a fundamental role in volume regulation and signaling. Currently, two plasma membrane-located anion channel familiesuSLAC/SLAH and ALMTuare known. Among the ALMT family, the root-expressed ALuminium-activated Malate Transporter 1 was identified by comparison of aluminum-tolerant and Al-3-sensitive wheat cultivars and was subsequently shown to mediate voltage-independent malate currents. In contrast, ALMT12/QUAC1 (QUickly activating Anion Channel1) is expressed in guard cells transporting malate in an Al-3-insensitive and highly voltage-dependent manner. So far, no information is available about the structure and mechanism of voltage-dependent gating with the QUAC1 channel protein. Here, we analyzed gating of QUAC1-type currents in the plasma membrane of guard cells and QUAC1-expressing oocytes revealing similar voltage dependencies and activationdeactivation kinetics. In the heterologous expression system, QUAC1 was electrophysiologically characterized at increasing extra- and intracellular malate concentrations. Thereby, malate additively stimulated the voltage-dependent QUAC1 activity. In search of structural determinants of the gating process, we could not identify transmembrane domains common for voltage-sensitive channels. However, site-directed mutations and deletions at the C-terminus of QUAC1 resulted in altered voltage-dependent channel activity. Interestingly, the replacement of a single glutamate residue, which is conserved in ALMT channels from different clades, by an alanine disrupted QUAC1 activity. Together with C- and N-terminal tagging, these results indicate that the cytosolic C-terminus is involved in the voltage-dependent gating mechanism of QUAC1.

@article{RN1083, abstract = {Here, we compared the highly voltage- and malate-dependent gating kinetics of R-/QUAC-type currents of guard cell protoplasts with QUAC1 expressed in oocytes. Truncations and mutation of QUAC1 indicated that the C-terminus is involved in the voltage-dependent gating mechanism of QUAC1.Anion transporters in plants play a fundamental role in volume regulation and signaling. Currently, two plasma membrane-located anion channel familiesuSLAC/SLAH and ALMTuare known. Among the ALMT family, the root-expressed ALuminium-activated Malate Transporter 1 was identified by comparison of aluminum-tolerant and Al-3-sensitive wheat cultivars and was subsequently shown to mediate voltage-independent malate currents. In contrast, ALMT12/QUAC1 (QUickly activating Anion Channel1) is expressed in guard cells transporting malate in an Al-3-insensitive and highly voltage-dependent manner. So far, no information is available about the structure and mechanism of voltage-dependent gating with the QUAC1 channel protein. Here, we analyzed gating of QUAC1-type currents in the plasma membrane of guard cells and QUAC1-expressing oocytes revealing similar voltage dependencies and activationdeactivation kinetics. In the heterologous expression system, QUAC1 was electrophysiologically characterized at increasing extra- and intracellular malate concentrations. Thereby, malate additively stimulated the voltage-dependent QUAC1 activity. In search of structural determinants of the gating process, we could not identify transmembrane domains common for voltage-sensitive channels. However, site-directed mutations and deletions at the C-terminus of QUAC1 resulted in altered voltage-dependent channel activity. Interestingly, the replacement of a single glutamate residue, which is conserved in ALMT channels from different clades, by an alanine disrupted QUAC1 activity. Together with C- and N-terminal tagging, these results indicate that the cytosolic C-terminus is involved in the voltage-dependent gating mechanism of QUAC1.}, added-at = {2024-02-14T14:38:32.000+0100}, author = {Mumm, P. and Imes, D. and Martinoia, E. and Al-Rasheid, K. A. S. and Geiger, D. and Marten, I. and Hedrich, R.}, biburl = {https://www.bibsonomy.org/bibtex/2014659b755f5ef5d3424c57f027c978f/rainerhedrich_2}, doi = {10.1093/mp/sst008}, interhash = {0ef99e63dad0f1b13d730d5947cceecc}, intrahash = {014659b755f5ef5d3424c57f027c978f}, issn = {1674-2052}, journal = {Molecular Plant}, keywords = {c-terminal deactivation myOwn}, note = {223sk Times Cited:43 Cited References Count:82}, number = 5, pages = {1550-1563}, timestamp = {2024-02-14T14:38:32.000+0100}, title = {C-Terminus-Mediated Voltage Gating of Guard Cell Anion Channel QUAC1}, type = {Journal Article}, url = {/brokenurl#<Go to ISI>://WOS:000324829400014}, volume = 6, year = 2013 }