ABCG36/PEN3/PDR8 Is an Exporter of the Auxin Precursor, Indole-3-Butyric Acid, and Involved in Auxin-Controlled Development

Aryal, Bibek; Huynh, John; Schneuwly, Jerôme; Siffert, Alexandra; Liu, Jie; Alejandro, Santiago; Ludwig‐Müller, Jutta; Martinoia, Enrico; Geisler, Markus

doi:10.3389/fpls.2019.00899

Cited by 28 publications

(36 citation statements)

References 50 publications

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“…IBA is transported over long distances by several carriers, including ABCG36/PEN3/PDR8 [ 42 ] and ABCG37/PDR9/PIS1 [ 42 – 44 ], both of which mediate IBA efflux through the plasma membrane (reviewed in [ 48 , 49 ]). These IBA transporters play important regulatory roles in cellular IBA levels (reviewed in [ 50 ]).…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, it has been reported that the ibr1 , 3 , 10 mutant displays small cotyledons [ 34 ]. More interestingly, mutants with defects in the IBA efflux carriers PENETRATION3 (PEN3; [ 42 ]) and PLEIOTROPIC DRUG RESISTANCE 9 (PDR9; [ 42 – 44 ]) have larger cotyledons, when compared to the WT, possibly due to high intracellular IBA, and thus higher endogenous IAA levels in these organs [ 42 ]. From these findings, IBA-derived IAA plays an important role not only in roots but also in plant shoots and particularly in cotyledons during their early developmental stage.…”

Section: Introductionmentioning

confidence: 99%

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An auxin signaling network translates low-sugar-state input into compensated cell enlargement in the fugu5 cotyledon

et al. 2021

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In plants, the effective mobilization of seed nutrient reserves is crucial during germination and for seedling establishment. The Arabidopsis H+-PPase-loss-of-function fugu5 mutants exhibit a reduced number of cells in the cotyledons. This leads to enhanced post-mitotic cell expansion, also known as compensated cell enlargement (CCE). While decreased cell numbers have been ascribed to reduced gluconeogenesis from triacylglycerol, the molecular mechanisms underlying CCE remain ill-known. Given the role of indole 3-butyric acid (IBA) in cotyledon development, and because CCE in fugu5 is specifically and completely cancelled by ech2, which shows defective IBA-to-indoleacetic acid (IAA) conversion, IBA has emerged as a potential regulator of CCE. Here, to further illuminate the regulatory role of IBA in CCE, we used a series of high-order mutants that harbored a specific defect in IBA-to-IAA conversion, IBA efflux, IAA signaling, or vacuolar type H+-ATPase (V-ATPase) activity and analyzed the genetic interaction with fugu5–1. We found that while CCE in fugu5 was promoted by IBA, defects in IBA-to-IAA conversion, IAA response, or the V-ATPase activity alone cancelled CCE. Consistently, endogenous IAA in fugu5 reached a level 2.2-fold higher than the WT in 1-week-old seedlings. Finally, the above findings were validated in icl–2, mls–2, pck1–2 and ibr10 mutants, in which CCE was triggered by low sugar contents. This provides a scenario in which following seed germination, the low-sugar-state triggers IAA synthesis, leading to CCE through the activation of the V-ATPase. These findings illustrate how fine-tuning cell and organ size regulation depend on interplays between metabolism and IAA levels in plants.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An auxin signaling network translates low-sugar-state input into compensated cell enlargement in the fugu5 cotyledon

et al. 2021

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“…However, their folds in a family are highly conserved, thus homology modeling can provide high-quality models [34][35][36][37]. We chose AtABCG36/PEN3/PDR8 [38] from the model plant Arabidopsis thaliana, which is a well-investigated full transporter of the ABCG subclass for that no structures yet exist. When the homology model exhibiting two ABCG2-like TMDs (Fig.…”

Section: Af2 Can Provide Hints For Investigating Abc Structure-associ...mentioning

confidence: 99%

Ins and outs of AlphaFold2 transmembrane protein structure predictions

Hegedüs

Geisler

Lukacs

et al. 2022

Cell. Mol. Life Sci.

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104

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Transmembrane (TM) proteins are major drug targets, but their structure determination, a prerequisite for rational drug design, remains challenging. Recently, the DeepMind’s AlphaFold2 machine learning method greatly expanded the structural coverage of sequences with high accuracy. Since the employed algorithm did not take specific properties of TM proteins into account, the reliability of the generated TM structures should be assessed. Therefore, we quantitatively investigated the quality of structures at genome scales, at the level of ABC protein superfamily folds and for specific membrane proteins (e.g. dimer modeling and stability in molecular dynamics simulations). We tested template-free structure prediction with a challenging TM CASP14 target and several TM protein structures published after AlphaFold2 training. Our results suggest that AlphaFold2 performs well in the case of TM proteins and its neural network is not overfitted. We conclude that cautious applications of AlphaFold2 structural models will advance TM protein-associated studies at an unexpected level.

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“…We included also ABCG37/PDR7/PIS1, shown to act redundantly with ABCG36 in IBA transport, and ABCG35, the closest homolog of ABCG36 (81.1% sequence identity), and both were also negative. We tested the same set also for IBA transport and discovered that all tested ABCGs were capable of exporting IBA, although ABCG34, G35 and G40 to a lesser amount than ABCG36 and G37 (Aryal et al, 2019;Ruzicka et al, 2010;Fig. 1B).…”

Section: Abcg36 Is An Exporter Of Camalexin That Functionally Interac...mentioning

confidence: 96%

A phospho-switch provided by LRR receptor-like kinase, ALK1/QSK1/KIN7, prioritizes ABCG36/PEN3/PDR8 transport toward defense

Aryal

Xia

et al. 2022

Preprint

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Based on its proposed substrate preferences, the ABC transporter, ABCG36/PDR8/PEN3, from the model plant Arabidopsis stands at the cross-road between growth and defence. Recently, ABCG36 was shown to export a few indolic compounds, including the auxin precursor, indole-3-butyric acid (IBA), and to be implicated in the export of the major phytoalexin of Arabidopsis, camalexin, although clear-cut proof of camalexin transport activity is still lacking.Here we provide strong evidence that ABCG36 catalyses the direct, ATP-dependent export of camalexin over the plasma membrane, however, most likely in functional interplay with non-camalexin transporting ABCG isoforms. We identify the leucin-rich repeat receptor-like kinase, Auxin-induced LRR Kinase1 (ALK1/KIN7/QSK1), as a functional kinase to physically interact with and phosphorylate ABCG36. ABCG36 phosphorylation by ALK1 represses unilaterally IBA but not camalexin export leading to a prioritization of ABCG transport toward defense. As a consequence, phospho-dead mutants of ABCG36, like alk1 and abcg36 alleles, are hypersensitive toward infection with the root pathogen, F. oxysporum, caused by elevated fungal progression.Our findings indicate a novel, direct regulatory circuit between a receptor kinase and an ABC transporter determining transporter substrate specificity. It appears that growth and defense balance decisions in plants are performed on the transporter level by means of a reversible phospho-switch.

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ABCG36/PEN3/PDR8 Is an Exporter of the Auxin Precursor, Indole-3-Butyric Acid, and Involved in Auxin-Controlled Development

Cited by 28 publications

References 50 publications

An auxin signaling network translates low-sugar-state input into compensated cell enlargement in the fugu5 cotyledon

An auxin signaling network translates low-sugar-state input into compensated cell enlargement in the fugu5 cotyledon

Ins and outs of AlphaFold2 transmembrane protein structure predictions

A phospho-switch provided by LRR receptor-like kinase, ALK1/QSK1/KIN7, prioritizes ABCG36/PEN3/PDR8 transport toward defense

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