<i>Arabidopsis thaliana <scp>FLA</scp>4</i> functions as a glycan‐stabilized soluble factor via its carboxy‐proximal Fasciclin 1 domain

Xue, Hui; Veit, Christiane; Abas, Lindy; Tryfona, Theodora; Maresch, Daniel; Ricardi, Martiniano María; Estevez, José M.; Strasser, Richard; Seifert, Georg

doi:10.1111/tpj.13591

Cited by 47 publications

(67 citation statements)

References 97 publications

(127 reference statements)

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“…V-AGP21 ALA , however, never reached the cell surface; retention in the secretory pathway could indicate that O -glycans direct AGP to the PM–cell surface ( Figure S2A–B ). These data corroborate previous reports of a requirement for O -glycans in the secretion and targeting of AGPs and related fasciclin-like AGPs [22,23].…”

Section: Resultssupporting

confidence: 92%

A cell surface arabinogalactan-peptide influences root hair cell fate

Borassi

Ricardi

Dorosz

et al. 2019

Preprint

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SummaryRoot hairs (RHs) develop from specialized epidermal cells called trichoblasts, whereas epidermal cells that lack RHs are known as atrichoblasts. The mechanism controlling root epidermal cell fate is only partially understood. Root epidermis cell fate is regulated by a transcription factor complex that promotes the expression of the homeodomain protein GLABRA 2 (GL2), which blocks RH development by inhibiting ROOT HAIR DEFECTIVE 6 (RHD6). Suppression of GL2 expression activates RHD6, a series of downstream TFs including ROOT HAIR DEFECTIVE 6 LIKE-4 (RSL4 [Yi et al. 2010]) and their target genes, and causes epidermal cells to develop into RHs. Brassinosteroids (BRs) influence root epidermis cell fate. In the absence of BRs, phosphorylated BIN2 (a Type-II GSK3-like kinase) inhibits a protein complex that directly downregulates GL2 [Chen et al. 2014]. Here, we show that the genetic and pharmacological perturbation of the arabinogalactan peptide (AG) AGP21 in Arabidopsis thaliana, triggers aberrant RH development, similar to that observed in plants with defective BR signaling. We reveal that an O-glycosylated AGP21 peptide, which is positively regulated by BZR1, a transcription factor activated by BR signaling, affects RH cell fate by altering GL2 expression in a BIN2-dependent manner. These results suggest that perturbation of a cell surface AGP disrupts BR responses and inhibits the downstream effect of BIN2 on the RH repressor GL2 in root epidermal cells. In addition, AGP21 also acts in a BR-independent, AGP-dependent mode that together with BIN2 signalling cascade controls RH cell fate.SignificanceIn the plant Arabidopsis thaliana, the root epidermis forms in an alternating pattern atrichoblasts with trichoblast cells that end up developing root hairs (RHs). Atrichoblast cell fate is directly promoted by the transcription factor GLABRA2 (GL2) while the lack of GL2 allows RH formation. The loss of AGP21 peptide triggers an abnormal RH cell fate in two contiguous cells in a similar manner as brassinosteroid (BRs) mutants. In the absence of BR signaling, BIN2 (a GSK3 like-kinase) in a phosphorylated state, downregulate GL2 expression to trigger RH cell fate. The absence of AGP21 is able to repress GL2 expression and activates the expression of RSL4 and EXP7 root hair proteins.

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Section: Resultssupporting

confidence: 92%

A cell surface arabinogalactan-peptide influences root hair cell fate

Borassi

Ricardi

Dorosz

et al. 2019

Preprint

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“…Disruption of the GPI anchor signal sequence, or blocking GPI anchor synthesis, resulted in accumulation of PMEI1 in the Golgi stacks. Based on this study and others in plants where disruption of GPI anchor synthesis or attachment results in mis-localization (Gillmor et al 2005;Dai et al 2014;Xue et al 2017), the GPI anchor may act as a sorting signal during secretion, similar to yeast and animals.…”

Section: Biosynthesis Of Gpi-anchored Proteins In Plantssupporting

confidence: 55%

Plant glycosylphosphatidylinositol anchored proteins at the plasma membrane‐cell wall nexus

Yeats

Bacic

Johnson

2018

JIPB

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Approximately 1% of plant proteins are predicted to be post-translationally modified with a glycosylphosphatidylinositol (GPI) anchor that tethers the polypeptide to the outer leaflet of the plasma membrane. Whereas the synthesis and structure of GPI anchors is largely conserved across eukaryotes, the repertoire of functional domains present in the GPI-anchored proteome has diverged substantially. In plants, this includes a large fraction of the GPI-anchored proteome being further modified with plant-specific arabinogalactan (AG) O-glycans. The importance of the GPI-anchored proteome to plant development is underscored by the fact that GPI biosynthetic null mutants exhibit embryo lethality. Mutations in genes encoding specific GPI-anchored proteins (GAPs) further supports their contribution to diverse biological processes, occurring at the interface of the plasma membrane and cell wall, including signaling, cell wall metabolism, cell wall polymer cross-linking, and plasmodesmatal transport. Here, we review the literature concerning plant GPI-anchored proteins, in the context of their potential to act as molecular hubs that mediate interactions between the plasma membrane and the cell wall, and their potential to transduce the signal into the protoplast and, thereby, activate signal transduction pathways.

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“…9 By contrast, the interaction model between FEI1 and Fas1-2 showed multiple interaction sites. To understand the driving force of the specific interaction, it is important to determine the characteristics of the protein interfaces.…”

Section: Resultsmentioning

confidence: 95%

“…6–8 Sequence searches suggest that every angiosperm genome contains at least one putative orthologue of FLA4 containing both, the N-proximal Fas1-1 and the C-proximal Fas1–2 domain in tandem. Therefore, it was surprising that, in a study previously published in The Plant Journal, 9 FLA4 exerted its role for root growth depending exclusively on Fas1-2 and did not require Fas1-1 for its function. Both full-length FLA4-citrin (F4C) constructs as well as a F4C construct lacking the Fas1-1 ( F4C∆Fas1-1 ) restored normal root growth to sos5 mutants.…”

Section: Resultsmentioning

confidence: 99%

A speculation on the tandem fasciclin 1 repeat of FLA4 proteins in angiosperms

Turupcu

Almohamed

Oostenbrink

et al. 2018

Plant Signaling & Behavior

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The Arabidopsis thaliana Fasciclin like arabinogalactan protein 4 (FLA4) locus is required for normal root growth in a linear genetic pathway with the FEI1 and FEI2 loci coding for receptor-like kinases. The two Fas1 domains of FLA4 are conserved among angiosperms but only the C-terminal Fas1 domain is required for genetic function. We show that at low salt deletion of the N-terminal Fas1 domain of transgenic FLA4 leads to enhanced root elongation compared to the tandem Fas1 wild type version. Modeling the hypothetical interaction between FLA4 and FEI1 we show that the predicted interaction is predominantly involving the C-terminal Fas1 domain. Relative conformational mobility between the two FLA4 Fas1 domains might regulate the interaction with the FEI receptor kinases. We therefore speculate that the FLA4 FEI complex might be a sensor for environmental conditions in the apoplast.

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Arabidopsis thaliana FLA4 functions as a glycan‐stabilized soluble factor via its carboxy‐proximal Fasciclin 1 domain

Cited by 47 publications

References 97 publications

A cell surface arabinogalactan-peptide influences root hair cell fate

A cell surface arabinogalactan-peptide influences root hair cell fate

Plant glycosylphosphatidylinositol anchored proteins at the plasma membrane‐cell wall nexus

A speculation on the tandem fasciclin 1 repeat of FLA4 proteins in angiosperms

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