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Trofimov K, Gratz R, Ivanov R, Stahl Y, Bauer P, Brumbarova T. FER-like iron deficiency-induced transcription factor (FIT) accumulates in nuclear condensates. J Cell Biol 2024; 223:e202311048. [PMID: 38393070 PMCID: PMC10890924 DOI: 10.1083/jcb.202311048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 12/28/2023] [Accepted: 01/23/2024] [Indexed: 02/25/2024] Open
Abstract
The functional importance of nuclear protein condensation remains often unclear. The bHLH FER-like iron deficiency-induced transcription factor (FIT) controls iron acquisition and growth in plants. Previously described C-terminal serine residues allow FIT to interact and form active transcription factor complexes with subgroup Ib bHLH factors such as bHLH039. FIT has lower nuclear mobility than mutant FITmSS271AA. Here, we show that FIT undergoes a light-inducible subnuclear partitioning into FIT nuclear bodies (NBs). Using quantitative and qualitative microscopy-based approaches, we characterized FIT NBs as condensates that were reversible and likely formed by liquid-liquid phase separation. FIT accumulated preferentially in NBs versus nucleoplasm when engaged in protein complexes with itself and with bHLH039. FITmSS271AA, instead, localized to NBs with different dynamics. FIT colocalized with splicing and light signaling NB markers. The NB-inducing light conditions were linked with active FIT and elevated FIT target gene expression in roots. FIT condensation may affect nuclear mobility and be relevant for integrating environmental and Fe nutrition signals.
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Affiliation(s)
- Ksenia Trofimov
- Institute of Botany, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Regina Gratz
- Institute of Botany, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Rumen Ivanov
- Institute of Botany, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Yvonne Stahl
- Institute for Developmental Genetics, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Cluster of Excellence on Plant Science (CEPLAS), Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Petra Bauer
- Institute of Botany, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Cluster of Excellence on Plant Science (CEPLAS), Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Tzvetina Brumbarova
- Institute of Botany, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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2
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Bizjak T, Sellstedt A, Gratz R, Nordin A. Presence and activity of nitrogen-fixing bacteria in Scots pine needles in a boreal forest: a nitrogen-addition experiment. Tree Physiol 2023; 43:1354-1364. [PMID: 37073466 PMCID: PMC10423461 DOI: 10.1093/treephys/tpad048] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 04/11/2023] [Indexed: 05/03/2023]
Abstract
Endophytic nitrogen-fixing bacteria have been detected and isolated from the needles of conifer trees growing in North American boreal forests. Because boreal forests are nutrient-limited, these bacteria could provide an important source of nitrogen for tree species. This study aimed to determine their presence and activity in a Scandinavian boreal forest, using immunodetection of nitrogenase enzyme subunits and acetylene-reduction assays of native Scots pine (Pinus sylvestris L.) needles. The presence and rate of nitrogen fixation by endophytic bacteria were compared between control plots and fertilized plots in a nitrogen-addition experiment. In contrast to the expectation that nitrogen-fixation rates would decline in fertilized plots, as seen, for instance, with nitrogen-fixing bacteria associated with bryophytes, there was no difference in the presence or activity of nitrogen-fixing bacteria between the two treatments. The extrapolated calculated rate of nitrogen fixation relevant for the forest stand was 20 g N ha-1 year-1, which is rather low compared with Scots pine annual nitrogen use but could be important for the nitrogen-poor forest in the long term. In addition, of 13 colonies of potential nitrogen-fixing bacteria isolated from the needles on nitrogen-free media, 10 showed in vitro nitrogen fixation. In summary, 16S rRNA sequencing identified the species as belonging to the genera Bacillus, Variovorax, Novosphingobium, Sphingomonas, Microbacterium and Priestia, which was confirmed by Illumina whole-genome sequencing. Our results confirm the presence of endophytic nitrogen-fixing bacteria in Scots pine needles and suggest that they could be important for the long-term nitrogen budget of the Scandinavian boreal forest.
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Affiliation(s)
- Tinkara Bizjak
- Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden
| | - Anita Sellstedt
- Umeå Plant Science Centre (UPSC), Department of Plant Physiology, Umeå University, 901 87 Umeå, Sweden
| | - Regina Gratz
- Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden
| | - Annika Nordin
- Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden
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Hornbergs J, Montag K, Loschwitz J, Mohr I, Poschmann G, Schnake A, Gratz R, Brumbarova T, Eutebach M, Angrand K, Fink-Straube C, Stühler K, Zeier J, Hartmann L, Strodel B, Ivanov R, Bauer P. SEC14-GOLD protein PATELLIN2 binds IRON-REGULATED TRANSPORTER1 linking root iron uptake to vitamin E. Plant Physiol 2023; 192:504-526. [PMID: 36493393 PMCID: PMC10152663 DOI: 10.1093/plphys/kiac563] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 09/23/2022] [Accepted: 12/07/2022] [Indexed: 05/03/2023]
Abstract
Organisms require micronutrients, and Arabidopsis (Arabidopsis thaliana) IRON-REGULATED TRANSPORTER1 (IRT1) is essential for iron (Fe2+) acquisition into root cells. Uptake of reactive Fe2+ exposes cells to the risk of membrane lipid peroxidation. Surprisingly little is known about how this is avoided. IRT1 activity is controlled by an intracellular variable region (IRT1vr) that acts as a regulatory protein interaction platform. Here, we describe that IRT1vr interacted with peripheral plasma membrane SEC14-Golgi dynamics (SEC14-GOLD) protein PATELLIN2 (PATL2). SEC14 proteins bind lipophilic substrates and transport or present them at the membrane. To date, no direct roles have been attributed to SEC14 proteins in Fe import. PATL2 affected root Fe acquisition responses, interacted with ROS response proteins in roots, and alleviated root lipid peroxidation. PATL2 had high affinity in vitro for the major lipophilic antioxidant vitamin E compound α-tocopherol. Molecular dynamics simulations provided insight into energetic constraints and the orientation and stability of the PATL2-ligand interaction in atomic detail. Hence, this work highlights a compelling mechanism connecting vitamin E with root metal ion transport at the plasma membrane with the participation of an IRT1-interacting and α-tocopherol-binding SEC14 protein.
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Affiliation(s)
- Jannik Hornbergs
- Institute of Botany, Heinrich Heine University, Düsseldorf 40225, Germany
| | - Karolin Montag
- Institute of Botany, Heinrich Heine University, Düsseldorf 40225, Germany
| | - Jennifer Loschwitz
- Institute of Theoretical Chemistry and Computer Chemistry, Heinrich Heine University, Düsseldorf 40225, Germany
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Inga Mohr
- Institute of Botany, Heinrich Heine University, Düsseldorf 40225, Germany
| | - Gereon Poschmann
- Institute of Molecular Medicine, Proteome Research, Medical Faculty and University Hospital, Heinrich-Heine-University Düsseldorf, Düsseldorf 40225, Germany
| | - Anika Schnake
- Institute for Molecular Ecophysiology of Plants, Heinrich Heine University, Düsseldorf 40225, Germany
| | - Regina Gratz
- Institute of Botany, Heinrich Heine University, Düsseldorf 40225, Germany
| | | | - Monique Eutebach
- Institute of Botany, Heinrich Heine University, Düsseldorf 40225, Germany
| | - Kalina Angrand
- Department of Biosciences-Plant Biology, Saarland University, Campus A2.4, D-66123 Saarbrücken, Germany
| | | | - Kai Stühler
- Institute of Molecular Medicine, Proteome Research, Medical Faculty and University Hospital, Heinrich-Heine-University Düsseldorf, Düsseldorf 40225, Germany
- Molecular Proteomics Laboratory, Heinrich Heine University, Düsseldorf 40225, Germany
| | - Jürgen Zeier
- Institute for Molecular Ecophysiology of Plants, Heinrich Heine University, Düsseldorf 40225, Germany
- Cluster of Excellence on Plant Science (CEPLAS), Heinrich Heine University, Düsseldorf 40225, Germany
| | - Laura Hartmann
- Institute of Macromolecular Chemistry, Heinrich Heine University, Düsseldorf 40225, Germany
| | - Birgit Strodel
- Institute of Theoretical Chemistry and Computer Chemistry, Heinrich Heine University, Düsseldorf 40225, Germany
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Rumen Ivanov
- Institute of Botany, Heinrich Heine University, Düsseldorf 40225, Germany
| | - Petra Bauer
- Institute of Botany, Heinrich Heine University, Düsseldorf 40225, Germany
- Cluster of Excellence on Plant Science (CEPLAS), Heinrich Heine University, Düsseldorf 40225, Germany
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Chandra A, Tünnermann L, Löfstedt T, Gratz R. Transformer-based deep learning for predicting protein properties in the life sciences. eLife 2023; 12:82819. [PMID: 36651724 PMCID: PMC9848389 DOI: 10.7554/elife.82819] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 01/06/2023] [Indexed: 01/19/2023] Open
Abstract
Recent developments in deep learning, coupled with an increasing number of sequenced proteins, have led to a breakthrough in life science applications, in particular in protein property prediction. There is hope that deep learning can close the gap between the number of sequenced proteins and proteins with known properties based on lab experiments. Language models from the field of natural language processing have gained popularity for protein property predictions and have led to a new computational revolution in biology, where old prediction results are being improved regularly. Such models can learn useful multipurpose representations of proteins from large open repositories of protein sequences and can be used, for instance, to predict protein properties. The field of natural language processing is growing quickly because of developments in a class of models based on a particular model-the Transformer model. We review recent developments and the use of large-scale Transformer models in applications for predicting protein characteristics and how such models can be used to predict, for example, post-translational modifications. We review shortcomings of other deep learning models and explain how the Transformer models have quickly proven to be a very promising way to unravel information hidden in the sequences of amino acids.
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Affiliation(s)
- Abel Chandra
- Department of Computing Science, Umeå UniversityUmeåSweden
| | - Laura Tünnermann
- Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural SciencesUmeåSweden
| | - Tommy Löfstedt
- Department of Computing Science, Umeå UniversityUmeåSweden
| | - Regina Gratz
- Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural SciencesUmeåSweden
- Department of Forest Ecology and Management, Swedish University of Agricultural SciencesUmeåSweden
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5
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Tünnermann L, Colou J, Näsholm T, Gratz R. To have or not to have: expression of amino acid transporters during pathogen infection. Plant Mol Biol 2022; 109:413-425. [PMID: 35103913 PMCID: PMC9213295 DOI: 10.1007/s11103-022-01244-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 01/16/2022] [Indexed: 06/14/2023]
Abstract
The interaction between plants and plant pathogens can have significant effects on ecosystem performance. For their growth and development, both bionts rely on amino acids. While amino acids are key transport forms of nitrogen and can be directly absorbed from the soil through specific root amino acid transporters, various pathogenic microbes can invade plant tissues to feed on different plant amino acid pools. In parallel, plants may initiate an immune response program to restrict this invasion, employing various amino acid transporters to modify the amino acid pool at the site of pathogen attack. The interaction between pathogens and plants is sophisticated and responses are dynamic. Both avail themselves of multiple tools to increase their chance of survival. In this review, we highlight the role of amino acid transporters during pathogen infection. Having control over the expression of those transporters can be decisive for the fate of both bionts but the underlying mechanism that regulates the expression of amino acid transporters is not understood to date. We provide an overview of the regulation of a variety of amino acid transporters, depending on interaction with biotrophic, hemibiotrophic or necrotrophic pathogens. In addition, we aim to highlight the interplay of different physiological processes on amino acid transporter regulation during pathogen attack and chose the LYSINE HISTIDINE TRANSPORTER1 (LHT1) as an example.
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Affiliation(s)
- Laura Tünnermann
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, 90183, Umeå, Sweden
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90183, Umeå, Sweden
| | - Justine Colou
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90183, Umeå, Sweden
| | - Torgny Näsholm
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90183, Umeå, Sweden
| | - Regina Gratz
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90183, Umeå, Sweden.
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6
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Gratz R, von der Mark C, Ivanov R, Brumbarova T. Fe acquisition at the crossroad of calcium and reactive oxygen species signaling. Curr Opin Plant Biol 2021; 63:102048. [PMID: 34015752 DOI: 10.1016/j.pbi.2021.102048] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/10/2021] [Accepted: 03/30/2021] [Indexed: 06/12/2023]
Abstract
Due to its redox properties, iron is both essential and toxic. Therefore, soil iron availability variations pose a significant problem for plants. Recent evidence suggests that calcium and reactive oxygen species coordinate signaling events related to soil iron acquisition. Calcium was found to affect directly IRT1-mediated iron import through the lipid-binding protein EHB1 and to trigger a CBL-CIPK-mediated signaling influencing the activity of the key iron-acquisition transcription factor FIT. In parallel, under prolonged iron deficiency, reactive oxygen species both inhibit FIT function and depend on FIT through the function of the catalase CAT2. We discuss the role of calcium and reactive oxygen species signaling in iron acquisition, with post-translational mechanisms influencing the localization and activity of iron-acquisition regulators and effectors.
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Affiliation(s)
- Regina Gratz
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
| | - Claudia von der Mark
- Group of Plant Vascular Development, Swiss Federal Institute of Technology (ETH) Zurich, 8092 Zurich, Switzerland
| | - Rumen Ivanov
- Institute of Botany, Heinrich Heine University, 40225 Düsseldorf, Germany
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7
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Gratz R, Ahmad I, Svennerstam H, Jämtgård S, Love J, Holmlund M, Ivanov R, Ganeteg U. Organic nitrogen nutrition: LHT1.2 protein from hybrid aspen (Populus tremula L. x tremuloides Michx) is a functional amino acid transporter and a homolog of Arabidopsis LHT1. Tree Physiol 2021; 41:1479-1496. [PMID: 33631788 PMCID: PMC8359683 DOI: 10.1093/treephys/tpab029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 02/05/2021] [Indexed: 06/12/2023]
Abstract
The contribution of amino acids (AAs) to soil nitrogen (N) fluxes is higher than previously thought. The fact that AA uptake is pivotal for N nutrition in boreal ecosystems highlights plant AA transporters as key components of the N cycle. At the same time, very little is known about AA transport and respective transporters in trees. Tree genomes may contain 13 or more genes encoding the lysine histidine transporter (LHT) family proteins, and this complicates the study of their significance for tree N-use efficiency. With the strategy of obtaining a tool to study N-use efficiency, our aim was to identify and characterize a relevant AA transporter in hybrid aspen (Populus tremula L. x tremuloides Michx.). We identified PtrLHT1.2, the closest homolog of Arabidopsis thaliana (L.) Heynh AtLHT1, which is expressed in leaves, stems and roots. Complementation of a yeast AA uptake mutant verified the function of PtrLHT1.2 as an AA transporter. Furthermore, PtrLHT1.2 was able to fully complement the phenotypes of the Arabidopsis AA uptake mutant lht1 aap5, including early leaf senescence-like phenotype, reduced growth, decreased plant N levels and reduced root AA uptake. Amino acid uptake studies finally showed that PtrLHT1.2 is a high affinity transporter for neutral and acidic AAs. Thus, we identified a functional AtLHT1 homolog in hybrid aspen, which harbors the potential to enhance overall plant N levels and hence increase biomass production. This finding provides a valuable tool for N nutrition studies in trees and opens new avenues to optimizing tree N-use efficiency.
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Affiliation(s)
- Regina Gratz
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
| | - Iftikhar Ahmad
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
| | - Henrik Svennerstam
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
| | - Sandra Jämtgård
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
| | - Jonathan Love
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
| | - Mattias Holmlund
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
| | - Rumen Ivanov
- Institute of Botany, Heinrich Heine University, 40225 Düsseldorf, Germany
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8
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Gratz R, Brumbarova T, Ivanov R, Trofimov K, Tünnermann L, Ochoa-Fernandez R, Blomeier T, Meiser J, Weidtkamp-Peters S, Zurbriggen MD, Bauer P. Phospho-mutant activity assays provide evidence for alternative phospho-regulation pathways of the transcription factor FER-LIKE IRON DEFICIENCY-INDUCED TRANSCRIPTION FACTOR. New Phytol 2020; 225:250-267. [PMID: 31487399 PMCID: PMC6916400 DOI: 10.1111/nph.16168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 08/16/2019] [Indexed: 05/03/2023]
Abstract
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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Affiliation(s)
- Regina Gratz
- Institute of Botany, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Tzvetina Brumbarova
- Institute of Botany, Heinrich-Heine University, 40225, Düsseldorf, Germany
- Department of Biosciences-Plant Biology, Saarland University, 66123, Saarbruecken, Germany
| | - Rumen Ivanov
- Institute of Botany, Heinrich-Heine University, 40225, Düsseldorf, Germany
- Department of Biosciences-Plant Biology, Saarland University, 66123, Saarbruecken, Germany
| | - Ksenia Trofimov
- Institute of Botany, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Laura Tünnermann
- Institute of Botany, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Rocio Ochoa-Fernandez
- Institute of Synthetic Biology, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Tim Blomeier
- Institute of Synthetic Biology, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Johannes Meiser
- Department of Biosciences-Plant Biology, Saarland University, 66123, Saarbruecken, Germany
- Department of Oncology, Luxembourg Institute of Health, 1445, Strassen, Luxembourg
| | | | - Matias D Zurbriggen
- Institute of Synthetic Biology, Heinrich-Heine University, 40225, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Petra Bauer
- Institute of Botany, Heinrich-Heine University, 40225, Düsseldorf, Germany
- Department of Biosciences-Plant Biology, Saarland University, 66123, Saarbruecken, Germany
- Cluster of Excellence on Plant Sciences, Heinrich-Heine University, 40225, Düsseldorf, Germany
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9
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Khan I, Gratz R, Denezhkin P, Schott-Verdugo SN, Angrand K, Genders L, Basgaran RM, Fink-Straube C, Brumbarova T, Gohlke H, Bauer P, Ivanov R. Calcium-Promoted Interaction between the C2-Domain Protein EHB1 and Metal Transporter IRT1 Inhibits Arabidopsis Iron Acquisition. Plant Physiol 2019; 180:1564-1581. [PMID: 31040174 PMCID: PMC6752929 DOI: 10.1104/pp.19.00163] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/12/2019] [Indexed: 05/19/2023]
Abstract
Iron is a key transition element in the biosphere and is crucial for living organisms, although its cellular excess can be deleterious. Maintaining the balance of optimal iron availability in the model plant Arabidopsis (Arabidopsis thaliana) requires the precise operation of iron import through the principal iron transporter IRON-REGULATED TRANSPORTER1 (IRT1). Targeted inhibition of IRT1 can prevent oxidative stress, thus promoting plant survival. Here, we report the identification of an IRT1 inhibitor, namely the C2 domain-containing peripheral membrane protein ENHANCED BENDING1 (EHB1). EHB1 interacts with the cytoplasmically exposed variable region of IRT1, and we demonstrate that this interaction is greatly promoted by the presence of calcium. We found that EHB1 binds lipids characteristic of the plasma membrane, and the interaction between EHB1 and plant membranes is calcium-dependent. Molecular simulations showed that EHB1 membrane binding is a two-step process that precedes the interaction between EHB1 and IRT1. Genetic and physiological analyses indicated that EHB1 acts as a negative regulator of iron acquisition. The presence of EHB1 prevented the IRT1-mediated complementation of iron-deficient fet3fet4 yeast (Saccharomyces cerevisiae). Our data suggest that EHB1 acts as a direct inhibitor of IRT1-mediated iron import into the cell. These findings represent a major step in understanding plant iron acquisition, a process that underlies the primary production of bioavailable iron for land ecosystems.
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Affiliation(s)
- Imran Khan
- Institute of Botany, Heinrich-Heine University, D-40225 Düsseldorf, Germany
| | - Regina Gratz
- Institute of Botany, Heinrich-Heine University, D-40225 Düsseldorf, Germany
- Former address: Department of Biosciences-Plant Biology, Saarland University, D-66123 Saarbrücken, Germany
| | - Polina Denezhkin
- Former address: Department of Biosciences-Plant Biology, Saarland University, D-66123 Saarbrücken, Germany
| | - Stephan N Schott-Verdugo
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich-Heine University, D-40225 Düsseldorf, Germany
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, CL-3460000 Talca, Chile
| | - Kalina Angrand
- Former address: Department of Biosciences-Plant Biology, Saarland University, D-66123 Saarbrücken, Germany
| | - Lara Genders
- Institute of Botany, Heinrich-Heine University, D-40225 Düsseldorf, Germany
| | | | | | - Tzvetina Brumbarova
- Institute of Botany, Heinrich-Heine University, D-40225 Düsseldorf, Germany
- Former address: Department of Biosciences-Plant Biology, Saarland University, D-66123 Saarbrücken, Germany
| | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich-Heine University, D-40225 Düsseldorf, Germany
- John von Neumann Institute for Computing, Jülich Supercomputing Centre & Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
| | - Petra Bauer
- Institute of Botany, Heinrich-Heine University, D-40225 Düsseldorf, Germany
- Former address: Department of Biosciences-Plant Biology, Saarland University, D-66123 Saarbrücken, Germany
- Cluster of Excellence on Plant Sciences, Heinrich-Heine University, D-40225 Düsseldorf, Germany
| | - Rumen Ivanov
- Institute of Botany, Heinrich-Heine University, D-40225 Düsseldorf, Germany
- Former address: Department of Biosciences-Plant Biology, Saarland University, D-66123 Saarbrücken, Germany
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10
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Abstract
This paper examined the ergonomics of child care at a large metropolitan, university-based child care center. A case study approach was used to describe the job analysis process and results. Center staff were involved in the identification of health risk factors by completing an ergonomics survey and responding to questions posed during the job analysis (n=36). Two occupational therapists analyzed six different rooms, accommodating different age groups of children. Specific activities were identified as stressors and/or health risk factors inherent in the jobs according to the age of the children cared for. A list of ergonomic health risk factors and recommendations was generated.
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Affiliation(s)
- P M King
- Occupational Therapy Program, University of Wisconsin - Milwaukee, P.O. Box 413, Milwaukee, WI 53201, USA
| | - R Gratz
- Department of Health Sciences, University of Wisconsin - Milwaukee, P.O. Box 413, Milwaukee, WI 53201, USA
| | - G Scheuer
- Waukesha Physical Therapy Services, 21075 Swenson Drive, Suite 600, Waukesha, WI 53186, USA
| | - A Claffey
- Child Care Center, University of Wisconsin - Milwaukee, P.O. Box 413, Milwaukee, WI 53201, USA
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11
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Abstract
Septic arthritis is usually of hematogenous origin and is increasingly being reported in elderly patients, who often have underlying medical conditions such as diabetes or alcoholism. We report a 62-year-old patient with alcoholic liver disease who presented with Escherichia coli bacteremia and septic arthritis in a previously fractured ankle. There are scarce reports of infectious arthritis in cirrhotic patients, but this is the first report of arthritis after a primary enteric bacteremia. We believe that the patient described here developed E. coli bacteremia as a result of bacterial overgrowth and translocation related to alcoholic liver disease and cirrhosis. The resulting bacteremia resulted in the development of infection in the left ankle, which had preexisting disease and was thus vulnerable. This case provides further evidence for the mode of infection being bacteremia in cirrhotic patients. In patients with cirrhosis and fever, a high index of suspicion is required for joint infection as a potential cause of fever or deterioration in the cirrhotic's patient general condition.
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Affiliation(s)
- S D Malnick
- Department of Internal Medicine C, Kaplan Medical Center, Rehovot, Israel
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Abstract
We describe a 77-year-old woman who developed fatigue, fever, a maculopapular rash and severe cholestatic hepatitis two weeks after receiving cloxacillin and ofloxacin.
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Affiliation(s)
- S Goland
- Department of Internal Medicine C, Kaplan Hospital, Rehovot, Israel
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