The structural bases for agonist diversity in an
            <i>Arabidopsis thaliana</i>
            glutamate receptor-like channel

Alfieri, Andrea; Doccula, Fabrizio Gandolfo; Pederzoli, Riccardo; Grenzi, Matteo; Bonza, Maria Cristina; Luoni, Laura; Candeo, Alessia; Romano-Armada, Neli; Barbiroli, Alberto; Valentini, Gianluca; Schneider, Thomas R.; Bassi, Andrea; Bolognesi, M.; Nardini, M.; Costa, Alex

doi:10.1073/pnas.1905142117

Cited by 69 publications

(53 citation statements)

References 63 publications

(81 reference statements)

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“…ACC is thus a candidate ligand of the GLR channel family. The range of effects, from strongest activation (ACC) to strongest inhibition (CNQX), is also suggestive of a direct action of the amino acid on Pp GLR1, consistent with what is now known from the interaction of amino acids with the ligand-binding domain of At GLR3.3 35 .…”

Section: Resultssupporting

confidence: 81%

“…The apparent promiscuity of GLR agonists arguably suggests that GLRs are adapted to functions where they process information associated with various amino acids. This view recently received support from a structural analysis of the At GLR3.3 ligand-binding domain 35 , raising the possibility that a preferred ligand in plants remains unaccounted for. Because Arabidopsis evolved twenty GLRs (more than humans), angiosperm GLRs constitute a challenging model for elucidating ligand specificity 17 , 33 , 34 .…”

Section: Resultsmentioning

confidence: 99%

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Ethylene-independent signaling by the ethylene precursor ACC in Arabidopsis ovular pollen tube attraction

et al. 2020

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The phytohormone ethylene has numerous effects on plant growth and development. Its immediate precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), is a non-proteinogenic amino acid produced by ACC SYNTHASE (ACS). ACC is often used to induce ethylene responses. Here, we demonstrate that ACC exhibits ethylene-independent signaling in Arabidopsis thaliana reproduction. By analyzing an acs octuple mutant with reduced seed set, we find that ACC signaling in ovular sporophytic tissue is involved in pollen tube attraction, and promotes secretion of the pollen tube chemoattractant LURE1.2. ACC activates Ca 2+-containing ion currents via GLUTAMATE RECEPTOR-LIKE (GLR) channels in root protoplasts. In COS-7 cells expressing moss PpGLR1, ACC induces the highest cytosolic Ca 2+ elevation compared to all twenty proteinogenic amino acids. In ovules, ACC stimulates transient Ca 2+ elevation, and Ca 2+ influx in octuple mutant ovules rescues LURE1.2 secretion. These findings uncover a novel ACC function and provide insights for unraveling new physiological implications of ACC in plants.

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Ethylene-independent signaling by the ethylene precursor ACC in Arabidopsis ovular pollen tube attraction

et al. 2020

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“…2019; Alfieri et al . 2020; Mayer, 2020). All human subfamilies serve unique and essential roles in neuronal circuit function.…”

Section: Introductionmentioning

confidence: 99%

Hodgkin–Huxley–Katz Prize Lecture: Genetic and pharmacological control of glutamate receptor channel through a highly conserved gating motif

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Myers

Yuan

et al. 2020

The Journal of Physiology

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Glutamate receptors are essential ligand-gated ion channels in the central nervous system that mediate excitatory synaptic transmission in response to the release of glutamate from presynaptic terminals. The structural and biophysical basis underlying the function of these receptors has been studied for decades by a wide range of approaches. However recent structural, pharmacological and genetic studies have provided new insight into the regions of this protein that are critical determinants of receptor function. Lack of variation in specific areas of the protein amino acid sequences in the human population has defined three regions in each receptor subunit that are under selective pressure, which has focused research efforts and driven new hypotheses. In addition, these three closely positioned elements reside near a cavity that is shown by multiple studies to be a likely site of action for allosteric modulators, one of which is currently in use as an FDA-approved anticonvulsant. These structural elements are capable of controlling gating of the pore, and appear to permit some modulators bound within the cavity to also alter permeation properties. This creates a new precedent whereby features of the channel pore can be modulated by exogenous drugs that bind outside the pore. The convergence of structural, genetic, biophysical and pharmacological approaches is a powerful means to gain insight into the complex biological processes defined by neurotransmitter receptor function.

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“…In Arabidopsis this scenario is supported by two pieces of evidence: (1) the use of the genetically encoded glutamate fluorescent sensor (iGluSnFR) reported a local increase in the apoplastic Glu concentration of the wounded leaf (Toyota et al ., 2018); and (2) treatment of Arabidopsis leaves or roots with a high concentration of Glu triggered long‐distance Ca 2+ signaling (Toyota et al ., 2018; Shao et al ., 2020). Moreover, in Arabidopsis, several studies reported that Glu (and other AAs) induced free cytosolic Ca 2+ increase and plasma membrane (PM) depolarization in seedlings and root cells, two events dependent on At GLR3.3 (Qi et al ., 2006; Alfieri et al ., 2020) (Fig. 2b).…”

Section: How Do Plant Glrs Work?mentioning

confidence: 95%

Structural insights into long‐distance signal transduction pathways mediated by plant glutamate receptor‐like channels

et al. 2020

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In recent years, studies have shed light on the physiological role of plant glutamate receptor-like channels (GLRs). However, the mechanism by which these channels are activated, and in particular, what is the physiological role of their binding to amino acids, remains elusive. The first direct biochemical demonstration that the Arabidopsis thaliana GLR3.3 isoform binds glutamate and other amino acids in a low micromolar range of concentrations was only recently reported. The first crystal structures of the ligand-binding domains of AtGLR3.3 and AtGLR3.2 isoforms have also been released. We foresee that these new experimental pieces of evidence provide the basis for a better understanding of how GLRs are activated and modulated in different physiological responses.

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The structural bases for agonist diversity in an Arabidopsis thaliana glutamate receptor-like channel

Cited by 69 publications

References 63 publications

Ethylene-independent signaling by the ethylene precursor ACC in Arabidopsis ovular pollen tube attraction

Ethylene-independent signaling by the ethylene precursor ACC in Arabidopsis ovular pollen tube attraction

Hodgkin–Huxley–Katz Prize Lecture: Genetic and pharmacological control of glutamate receptor channel through a highly conserved gating motif

Structural insights into long‐distance signal transduction pathways mediated by plant glutamate receptor‐like channels

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