Mg2+ Is a Missing Link in Plant Cell Ca2+ Signalling and Homeostasis—A Study on Vicia faba Guard Cells
Type
ArticleKAUST Department
Biological and Environmental Sciences and Engineering (BESE) DivisionBioscience Program
Computational Bioscience Research Center (CBRC)
Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division
Molecular Signalling Group
Structural Biology and Engineering
Date
2020-05-27Submitted Date
2020-03-28Permanent link to this record
http://hdl.handle.net/10754/662959
Metadata
Show full item recordAbstract
Hyperpolarization-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 signalling. The unusual gating properties of HACCs in plants, i.e., activation by membrane hyperpolarization rather than depolarization, dictates that HACCs are normally open in the physiological hyperpolarized resting membrane potential state (the so-called pump or P-state); thus, if not regulated, they would continuously leak Ca2+ into cells. HACCs are permeable to Ca2+, Ba2+, and Mg2+; activated by H2O2 and the plant hormone abscisic acid (ABA); and their activity in guard cells is greatly reduced by increasing amounts of free cytosolic Ca2+ ([Ca2+]Cyt), and hence closes during [Ca2+]Cyt surges. Here, we demonstrate that the presence of the commonly used Mg-ATP inside the guard cell greatly reduces HACC activity, especially at voltages ≤ −200 mV, and that Mg2+ causes this block. Therefore, we firstly conclude that physiological cytosolic Mg2+ levels affect HACC gating and that channel opening requires either high negative voltages (≥ −200 mV) or displacement of Mg2+ away from the immediate vicinity of the channel. Secondly, based on structural comparisons with a 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 diacidic 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.Citation
Lemtiri-Chlieh, F., Arold, S. T., & Gehring, C. (2020). Mg2+ Is a Missing Link in Plant Cell Ca2+ Signalling and Homeostasis—A Study on Vicia faba Guard Cells. International Journal of Molecular Sciences, 21(11), 3771. doi:10.3390/ijms21113771Sponsors
This research has been supported by the King Abdullah University of Science and Technology (KAUST). We are indebted to Enid MacRobbie (Department of Plant Science, University of Cambridge, UK) for allowing us to use some of the data gathered by F.L.-C. whilst in her laboratory (research was supported by BBSRC Grant P05730 to E.M.). We also thank Mark Tester for his invaluable comments.Publisher
MDPI AGPubMed ID
32471040Additional Links
https://www.mdpi.com/1422-0067/21/11/3771https://www.mdpi.com/1422-0067/21/11/3771/pdf
ae974a485f413a2113503eed53cd6c53
10.3390/ijms21113771
Scopus Count
Related articles
- Identification of cyclic GMP-activated nonselective Ca2+-permeable cation channels and associated CNGC5 and CNGC6 genes in Arabidopsis guard cells.
- Authors: Wang YF, Munemasa S, Nishimura N, Ren HM, Robert N, Han M, Puzõrjova I, Kollist H, Lee S, Mori I, Schroeder JI
- Issue date: 2013 Oct
- A type of voltage-dependent Ca2+ channel on Vicia faba guard cell plasma membrane outwardly permeates K+.
- Authors: Chen DH, Wang M, Wang HG, Zhang W
- Issue date: 2012 Jul
- Hyperpolization-activated Ca(2+) channels in guard cell plasma membrane are involved in extracellular ATP-promoted stomatal opening in Vicia faba.
- Authors: Wang F, Jia J, Wang Y, Wang W, Chen Y, Liu T, Shang Z
- Issue date: 2014 Sep 1
- Open Stomata 1 (OST1) is limiting in abscisic acid responses of Arabidopsis guard cells.
- Authors: Acharya BR, Jeon BW, Zhang W, Assmann SM
- Issue date: 2013 Dec
- Actin dynamics regulates voltage-dependent calcium-permeable channels of the Vicia faba guard cell plasma membrane.
- Authors: Zhang W, Fan LM
- Issue date: 2009 Oct