The iron deficiency response in
            <i>Arabidopsis thaliana</i>
            requires the phosphorylated transcription factor URI

Kim, Sun A.; LaCroix, Ian S; Gerber, Scott A.; Guerinot, Mary Lou

doi:10.1073/pnas.1916892116

Cited by 127 publications

(134 citation statements)

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“…A latest study found that AtFIT promotes the nuclear accumulation of AtbHLH39, an Arabidopsis homolog of OsIRO2, in Arabidopsis (Trofimov et al, 2019). Similarly, Arabidopsis bHLH IVc TFs promote the nuclear accumulation of AtbHLH121 which is required for the maintenance of Arabidopsis Fe homeostasis (Kim et al, 2019; Gao et al, 2020; Lei et al, 2020). Although we did not observe the localization change of OsIRO2 in response to Fe deficiency in our transient expression assays, the increased nuclear accumulation of OsIRO2 under Fe deficiency condition was observed by Wang et al (2020).…”

Section: Discussionmentioning

confidence: 99%

FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT) interacts with OsIRO2 to regulate iron homeostasis

Liang

Zhang²,

et al. 2020

Preprint

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There are two Fe-uptake strategies for maintaining Fe homeostasis in plants. As a special graminaceous plant, rice applies both strategies. However, it remains unclear how these two strategies are regulated in rice. IRON-RELATED BHLH TRANSCRIPTION FACTOR 2 (OsIRO2) is critical for regulating Fe uptake in rice. In this study, we identified an interacting partner of OsIRO2, Oryza sativa FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT), which encodes a bHLH transcription factor. The OsIRO2 protein is localized in the cytoplasm and nucleus, but OsFIT facilitates the accumulation of OsIRO2 in the nucleus. Loss-of-function mutations to OsFIT result in decreased Fe accumulation, severe Fe-deficiency symptoms, and disrupted expression of Fe-uptake genes. In contrast, OsFIT overexpression promotes Fe accumulation and the expression of Fe-uptake genes. Genetic analyses indicated that OsFIT and OsIRO2 function in the same genetic node. Further analysis suggested that OsFIT and OsIRO2 form a functional transcription activation complex to initiate the expression of Fe-uptake genes. Our findings provide a mechanism understanding of how rice maintains Fe homeostasis.One-sentence summaryOsFIT interacts with and facilitates the accumulation of OsIRO2 in the nucleus where the OsFIT-OsIRO2 transcription complex initiates the transcription of Fe deficiency responsive genes.

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Section: Discussionmentioning

confidence: 99%

FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT) interacts with OsIRO2 to regulate iron homeostasis

Liang

Zhang²,

et al. 2020

Preprint

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“…A short time ago, another piece was added to the iron deficiency response puzzle [68]. Upstream Regulator of IRT1 (URI), basic helix-loop-helix transcription factor, appears to have a central role as an iron-dependent switch.…”

Section: Ups In the Regulation Of Iron Homeostasismentioning

confidence: 99%

The Role of Selective Protein Degradation in the Regulation of Iron and Sulfur Homeostasis in Plants

Wawrzyńska

Sirko

2020

IJMS

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Plants are able to synthesize all essential metabolites from minerals, water, and light to complete their life cycle. This plasticity comes at a high energy cost, and therefore, plants need to tightly allocate resources in order to control their economy. Being sessile, plants can only adapt to fluctuating environmental conditions, relying on quality control mechanisms. The remodeling of cellular components plays a crucial role, not only in response to stress, but also in normal plant development. Dynamic protein turnover is ensured through regulated protein synthesis and degradation processes. To effectively target a wide range of proteins for degradation, plants utilize two mechanistically-distinct, but largely complementary systems: the 26S proteasome and the autophagy. As both proteasomaland autophagy-mediated protein degradation use ubiquitin as an essential signal of substrate recognition, they share ubiquitin conjugation machinery and downstream ubiquitin recognition modules. Recent progress has been made in understanding the cellular homeostasis of iron and sulfur metabolisms individually, and growing evidence indicates that complex crosstalk exists between iron and sulfur networks. In this review, we highlight the latest publications elucidating the role of selective protein degradation in the control of iron and sulfur metabolism during plant development, as well as environmental stresses. are present at certain concentrations, i.e., when the demand meets the supply. Below such levels, the demand for a nutrient exceeds the supply, so plant growth is ultimately limited by a nutritional deficiency. Conversely, an excess of any nutrient is toxic to plants and also negatively affects plant growth and development. Plants can therefore experience transitions between deficiency or toxicity zones due to changes in the availability of nutrients and growth requirements, but they can return to homeostasis so long as the response is adequate and sufficient. Such adjustments may require time, but they are crucial for plant adaptation. A significant part of this adaptation relies on selective protein degradation (Figure 1). Int. J. Mol. Sci. 2020, 21, x FOR PEER REVIEW 2 of 21 nutrients are present at certain concentrations, i.e., when the demand meets the supply. Below such levels, the demand for a nutrient exceeds the supply, so plant growth is ultimately limited by a nutritional deficiency. Conversely, an excess of any nutrient is toxic to plants and also negatively affects plant growth and development. Plants can therefore experience transitions between deficiency or toxicity zones due to changes in the availability of nutrients and growth requirements, but they can return to homeostasis so long as the response is adequate and sufficient. Such adjustments may require time, but they are crucial for plant adaptation. A significant part of this adaptation relies on selective protein degradation ( Figure 1). Figure 1.Regulation of nutrient deficiency stress by ubiquitination. The plant perceives nutrient deficienc...

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“…These four members regulate the expression of FER-LIKE IRON-DEFICIENCY-INDUCED TRANSCRIPTION FACTOR ( FIT ), bHLH Ib genes ( bHLH38 , bHLH39 , bHLH100 , and bHLH101 ) and POPEYE ( PYE ) (Zhang et al 2015; Li et al 2016; Liang et al 2017). Recently, three studies characterized the functions of bHLH121 (Kim et al 2019; Gao et al 2020; Lei et al 2020), and Lei et al (2020) found that bHLH121 is also directly regulated by bHLH IVc. FIT interacts with bHLH Ib TFs and they synergistically promote the expression of Fe-uptake associated genes IRT1 and FRO2 (Yuan et al 2008; Wang et al 2013).…”

Section: Introductionmentioning

confidence: 99%

“…bHLH105/ILR3 also functions as a negative regulator when it interacts with PYE (Tissot et al 2019). In contrast, bHLH121 is required for activation of numerous Fe deficiency responsive genes (Kim et al 2019; Gao et al 2020; Lei et al 2020). Moreover, both bHLH 121 and PYE interact with bHLH IVc to regulate Fe homeostasis in Arabidopisis (Long et al 2010; Selote et al 2015; Kim et al 2019; Tissot et al 2019; Gao et al 2020; Lei et al 2020).…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, bHLH121 is required for activation of numerous Fe deficiency responsive genes (Kim et al 2019; Gao et al 2020; Lei et al 2020). Moreover, both bHLH 121 and PYE interact with bHLH IVc to regulate Fe homeostasis in Arabidopisis (Long et al 2010; Selote et al 2015; Kim et al 2019; Tissot et al 2019; Gao et al 2020; Lei et al 2020). There is also a similar Fe deficiency response signaling network in rice (Ogo et al 2007; Kobayashi 2013, 2019; Zhang et al 2017, 2020; Wang et al 2020; Li et al 2020).…”

Section: Introductionmentioning

confidence: 99%

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bHLH11 inhibits bHLH IVc proteins by recruiting the TOPLESS/TOPLESS-RELATED corepressors in Arabidopsis

Yang

Lei

et al. 2020

Preprint

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Iron (Fe) homeostasis is essential for plant growth and development. Although tremendous progress has been made in understanding the maintenance of Fe homeostasis in plants, the underlying molecular mechanisms remain elusive. Recently, bHLH11 was reported to function as a negative regulator. However, the molecular mechanism by which bHLH11 regulates Fe homeostasis is unclear. Here, we generated two bhlh11 loss-of-function mutants which displayed the enhanced sensitivity to excessive Fe. bHLH11 is located in the cytoplasm and nucleus due to lack of a nuclear location signal sequence, and its interaction partners, bHLH IVc transcription factors (TFs) (bHLH34, bHLH104, bHLH105 and bHLH115) facilitate its nuclear accumulation. bHLH11 exerts its negative regulation function by recruiting the corepressors TOPLESS/TOPLESS-RELATED. Moreover, bHLH11 antagonizes the transactivity of bHLH IVc TFs towards bHLH Ib genes (bHLH38, bHLH39, bHLH100 and bHLH101). This work indicates that bHLH11 is a crucial component of Fe homeostasis signaling network, playing a pivotal role in the fine-tuning of Fe homeostasis.

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The iron deficiency response in Arabidopsis thaliana requires the phosphorylated transcription factor URI

Cited by 127 publications

References 49 publications

FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT) interacts with OsIRO2 to regulate iron homeostasis

FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT) interacts with OsIRO2 to regulate iron homeostasis

The Role of Selective Protein Degradation in the Regulation of Iron and Sulfur Homeostasis in Plants

bHLH11 inhibits bHLH IVc proteins by recruiting the TOPLESS/TOPLESS-RELATED corepressors in Arabidopsis

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