%0 Journal Article %1 mumm2013cterminusmediated %A Mumm, Patrick %A Imes, Dennis %A Martinoia, Enrico %A Al-Rasheid, Khaled A S %A Geiger, Dietmar %A Marten, Irene %A Hedrich, Rainer %C England %D 2013 %J Molecular plant %K imported %N 5 %P 1550--1563 %R 10.1093/mp/sst008 %T C-terminus-mediated voltage gating of Arabidopsis guard cell anion channel QUAC1 %U https://pubmed.ncbi.nlm.nih.gov/23314055 %V 6 %X Anion transporters in plants play a fundamental role in volume regulation and signaling. Currently, two plasma membrane-located anion channel families—SLAC/SLAH and ALMT—are 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 activation–deactivation 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{mumm2013cterminusmediated, abstract = {Anion transporters in plants play a fundamental role in volume regulation and signaling. Currently, two plasma membrane-located anion channel families—SLAC/SLAH and ALMT—are 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 activation–deactivation 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 = {2024-02-16T13:33:38.000+0100}, address = {England}, author = {Mumm, Patrick and Imes, Dennis and Martinoia, Enrico and Al-Rasheid, Khaled A S and Geiger, Dietmar and Marten, Irene and Hedrich, Rainer}, biburl = {https://www.bibsonomy.org/bibtex/25f16e7cf2433fa7e4ea4a039a28e4487/imarten}, comment = {23314055[pmid]}, description = {C-terminus-mediated voltage gating of Arabidopsis guard cell anion channel QUAC1 - PubMed}, doi = {10.1093/mp/sst008}, interhash = {c7c1d1737ac14cbe78e52880dac794ea}, intrahash = {5f16e7cf2433fa7e4ea4a039a28e4487}, issn = {17529867}, journal = {Molecular plant}, keywords = {imported}, month = sep, number = 5, pages = {1550--1563}, timestamp = {2024-02-16T13:33:38.000+0100}, title = {C-terminus-mediated voltage gating of Arabidopsis guard cell anion channel QUAC1}, url = {https://pubmed.ncbi.nlm.nih.gov/23314055}, volume = 6, year = 2013 }