CIPK11-Dependent Phosphorylation Modulates FIT Activity to Promote Arabidopsis Iron Acquisition in Response to Calcium Signaling

Grätz, R.; Manishankar, Prabha; Ivanov, Rumen; Köster, Philipp; Mohr, Inga; Trofimov, Ksenia; Steinhorst, Leonie; Meiser, Johannes; Mai, Hans-Jörg; Drerup, Maria M.; Arendt, S.; Holtkamp, Michael; Kärst, Uwe; Kudla, Jörg; Bauer, Petra; Brumbarova, Tzvetina

doi:10.1016/j.devcel.2019.01.006

Cited by 93 publications

(150 citation statements)

References 66 publications

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“…The additional phosphorylation motifs XXpSPX (Kemp & Pearson, ; Beausoleil et al ., ; Luo et al ., ; Schwartz & Gygi, ) and SXXXpS (Fiol et al ., ) were found to enclose Ser271 and Ser272. This suggests that only one of the two neighboring Sers undergoes phosphorylation, to which we refer here as Ser272, which is concordant with our previous results (Gratz et al ., ). The highly conserved Tyr238 is part of the motif pYXX[L/I/V] (Argetsinger et al ., ).…”

Section: Resultsmentioning

confidence: 97%

“…d). With such a mutational approach, we recently showed relevance of Ser272 for FIT activity (Gratz et al ., ). In the course of our work presented here, FITm(S221E) turned out to be more active than WT FIT, whereas FITm(S221A) behaved rather neutrally.…”

Section: Resultsmentioning

confidence: 97%

“…Posttranslational phosphorylation affects protein properties, including subcellular localization (Ju et al ., ; Ren et al ., ; Takeo & Ito, ), and this is also the case for FIT (Gratz et al ., ). The cytoplasm‐to‐nucleus ratio of FIT localization is in the range of 3–5 (Fig.…”

Section: Resultsmentioning

confidence: 97%

“…Ser221 is conserved within the family of Brassicaceae, as well as in species belonging to the commelinids and fabids. The two serines Ser271 and Ser272, previously characterized by us as FIT phosphorylation targets (Gratz et al ., ), are conserved among the Brassicaceae. Interestingly, however, only one of the two Sers is conserved among members of the monocots, superasterids, and the remaining superrosids.…”

Section: Resultsmentioning

confidence: 99%

“…A small pool of FIT protein is phosphorylated, and calcium‐sensing CBL‐INTERACTING PROTEIN KINASE11 (CIPK11) targets position Ser272 of FIT and activates it. Ser272 is crucial for FIT to localize in the nucleus, interact with bHLH039, and activate FIT targets so that plants ultimately take up Fe and transport it to seeds (Gratz et al ., ). Interestingly, Ser272 is present in the C‐terminal part of FIT, which can be regarded as a regulatory domain of FIT, FIT‐C.…”

Section: Introductionmentioning

confidence: 97%

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Phospho‐mutant activity assays provide evidence for alternative phospho‐regulation pathways of the transcription factor FER‐LIKE IRON DEFICIENCY‐INDUCED TRANSCRIPTION FACTOR

et al. 2019

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Summary The key basic helix–loop–helix (bHLH) transcription factor in iron (Fe) uptake, FER‐LIKE IRON DEFICIENCY‐INDUCED TRANSCRIPTION FACTOR (FIT), is controlled by multiple signaling pathways, important to adjust Fe acquisition to growth and environmental constraints. FIT protein exists in active and inactive protein pools, and phosphorylation of serine Ser272 in the C‐terminus, a regulatory domain of FIT, provides a trigger for FIT activation. Here, we use phospho‐mutant activity assays and study phospho‐mimicking and phospho‐dead mutations of three additional predicted phosphorylation sites, namely at Ser221 and at tyrosines Tyr238 and Tyr278, besides Ser 272. Phospho‐mutations at these sites affect FIT activities in yeast, plant, and mammalian cells. The diverse array of cellular phenotypes is seen at the level of cellular localization, nuclear mobility, homodimerization, and dimerization with the FIT‐activating partner bHLH039, promoter transactivation, and protein stability. Phospho‐mimicking Tyr mutations of FIT disturb fit mutant plant complementation. Taken together, we provide evidence that FIT is activated through Ser and deactivated through Tyr site phosphorylation. We therefore propose that FIT activity is regulated by alternative phosphorylation pathways.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

See 3 more Smart Citations

Phospho‐mutant activity assays provide evidence for alternative phospho‐regulation pathways of the transcription factor FER‐LIKE IRON DEFICIENCY‐INDUCED TRANSCRIPTION FACTOR

et al. 2019

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Role of CBL‐Interacting Protein Kinases in Regulating Plant Stress Responses

Narayanan

Sanyal

Pandey

2020

Protein Kinases and Stress Signaling in Plants

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Mobility and localization of the iron deficiency‐induced transcription factor bHLH039 change in the presence of FIT

et al. 2019

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Regulation of iron (Fe) acquisition and homeostasis is critical for plant survival. In Arabidopsis, Fe deficiency‐induced bHLH039 forms a complex with the master regulator FIT and activates it to upregulate Fe acquisition genes. FIT is partitioned between cytoplasm and nucleus, whereby active FIT accumulates more in the nucleus than inactive FIT. At the same time, there is so far no information on the subcellular localization of bHLH039 protein and how it is controlled. We report here that the bHLH039 localization pattern changes depending on the presence of FIT in the cell. When expressed in cells lacking FIT, bHLH039 localizes predominantly in the cytoplasm, including cytoplasmic foci in close proximity to the plasma membrane. The presence of FIT enhances the mobility of bHLH039 and redirects the protein toward primarily nuclear localization, abolishing its accumulation in cytoplasmic foci. This FIT‐dependent change in localization of bHLH039 found in transient fluorescent protein expression experiments was confirmed in both leaves and roots of Arabidopsis transgenic plants, stably expressing hemagglutinin‐tagged bHLH039 in wild‐type or fit mutant background. This posttranslational mechanism for intracellular partitioning of Fe‐responsive transcription factors suggests a signaling cascade that translates Fe sensing at the plasma membrane to nuclear accumulation of the transcriptional regulators.

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CIPK11-Dependent Phosphorylation Modulates FIT Activity to Promote Arabidopsis Iron Acquisition in Response to Calcium Signaling

Cited by 93 publications

References 66 publications

Phospho‐mutant activity assays provide evidence for alternative phospho‐regulation pathways of the transcription factor FER‐LIKE IRON DEFICIENCY‐INDUCED TRANSCRIPTION FACTOR

Phospho‐mutant activity assays provide evidence for alternative phospho‐regulation pathways of the transcription factor FER‐LIKE IRON DEFICIENCY‐INDUCED TRANSCRIPTION FACTOR

Role of CBL‐Interacting Protein Kinases in Regulating Plant Stress Responses

Mobility and localization of the iron deficiency‐induced transcription factor bHLH039 change in the presence of FIT

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