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dc.contributor.authorLemtiri-Chlieh, Fouad
dc.contributor.authorArold, Stefan T.
dc.contributor.authorGehring, Christoph A
dc.identifier.citationLemtiri-Chlieh, F., Arold, S., & Gehring, C. (2020). Mg2+ modulates the activity of hyperpolarization-activated calcium currents in plant cells. doi:10.1101/2020.01.14.906123
dc.description.abstractHyperpolarization-activated calcium channels (HACCs) are found in the plasma membrane and tonoplast of many plant cell types where they have an important role in Ca2+-dependent signaling. The unusual gating properties of HACCs in plants, i.e., activation by membrane hyperpolarization rather than depolarization, dictates that HACCs are normally open at physiological hyperpolarized resting membrane potentials (the so called pump or P-state), thus, if not regulated, they would be continuously leaking Ca2+ into cells. In guard cells, HACCs are permeable to Ca2+, Ba2+ and Mg2+, activated by H2O2 and the plant hormone abscisic acid (ABA) and their activity is greatly reduced by low amounts of free cytosolic Ca2+ ([Ca2+]Cyt) and hence will close during [Ca2+]Cyt surges. Here we demonstrate that the presence of the commonly used Mg-ATP inside the cell greatly reduces HACC activity especially at voltages ≤ -200 mV and that Mg2+ causes this block. We therefore conclude, firstly, that physiological cytosolic Mg2+ levels affect HACCs gating and that channel opening requires either high negative voltages (≥ -200 mV) and/or displacement of Mg2+ away from the immediate vicinity of the channel. Secondly, based on structural comparisons with Mg2+-sensitive animal inward-rectifying K+ channel, we propose that the likely candidate HACCS described here are cyclic nucleotide gated channels (CNGCs), many of which also contain a conserved di-acidic Mg2+-binding motif within their pores. This conclusion is consistent with the,electrophysiological data. Finally, we propose that Mg2+, much like in animal cells, is an important component in Ca2+ signalling and homeostasis in plants.
dc.description.sponsorshipThis research has been supported by the King Abdullah University of Science and Technology (KAUST). We are indebted to Professor Enid MacRobbie (Department of Plant Science, University of Cambridge, UK) for allowing us to use some of the data gathered by FL-C while in her laboratory (research was supported by BBSRC Grant P05730 to E.M.). We also thank Prof. Mark Tester for his invaluable comments.
dc.publisherCold Spring Harbor Laboratory
dc.rightsArchived with thanks to Cold Spring Harbor Laboratory
dc.titleMg2+ modulates the activity of hyperpolarization-activated calcium currents in plant cells
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Division
dc.contributor.departmentBioscience Program
dc.contributor.departmentComputational Bioscience Research Center (CBRC)
dc.contributor.departmentComputer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division
dc.contributor.departmentMolecular Signalling Group
dc.contributor.departmentStructural Biology and Engineering
dc.contributor.institutionDepartment of Neuroscience, University of Connecticut School of Medicine, Farmington, CT 06030
dc.contributor.institutionCentre de Biochimie Structurale, CNRS, INSERM, Université de Montpellier, 34090 Montpellier, France
dc.contributor.institutionDepartment of Chemistry, Biology & Biotechnology, University of Perugia, ITALY
kaust.personLemtiri-Chlieh, Fouad
kaust.personArold, Stefan T.
kaust.personArold, Stefan T.
kaust.personGehring, Christoph A.

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Archived with thanks to Cold Spring Harbor Laboratory
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