title: Interaction between the bHLH transcription factor FIT and ETHYLENE INSENSITIVE3/ETHYLENE INSENSITIVE3-LIKE1 reveals molecular linkage between the regulation of iron acquisition and ethylene signaling in Arabidopsis.
abstract: Understanding the regulation of key genes involved in plant iron acquisition is of crucial importance for breeding of micronutrient-enriched crops. The basic helix-loop-helix protein FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT), a central regulator of Fe acquisition in roots, is regulated by environmental cues and internal requirements for iron at the transcriptional and posttranscriptional levels. The plant stress hormone ethylene promotes iron acquisition, but the molecular basis for this remained unknown. Here, we demonstrate a direct molecular link between ethylene signaling and FIT. We identified ETHYLENE INSENSITIVE3 (EIN3) and ETHYLENE INSENSITIVE3-LIKE1 (EIL1) in a screen for direct FIT interaction partners and validated their physical interaction in planta. We demonstrate that the ein3 eil1 transcriptome was affected to a greater extent upon iron deficiency than normal iron compared with the wild type. Ethylene signaling by way of EIN3/EIL1 was required for full-level FIT accumulation. FIT levels were reduced upon application of aminoethoxyvinylglycine and in the ein3 eil1 background. MG132 could restore FIT levels. We propose that upon ethylene signaling, FIT is less susceptible to proteasomal degradation, presumably due to a physical interaction between FIT and EIN3/EIL1. Increased FIT abundance then leads to the high level of expression of genes required for Fe acquisition. This way, ethylene is one of the signals that triggers Fe deficiency responses at the transcriptional and posttranscriptional levels.
authors.affiliation: Department of Biosciences-Plant Biology, Saarland University, Saarbrucken, Germany.
authors.forename: Sivasenkar
authors.initials: S
authors.lastname: Lingam
authors.forename: Julia
authors.initials: J
authors.lastname: Mohrbacher
authors.forename: Tzvetina
authors.initials: T
authors.lastname: Brumbarova
authors.forename: Thomas
authors.initials: T
authors.lastname: Potuschak
authors.forename: Claudia
authors.initials: C
authors.lastname: Fink-Straube
authors.forename: Eddy
authors.initials: E
authors.lastname: Blondet
authors.forename: Pascal
authors.initials: P
authors.lastname: Genschik
authors.forename: Petra
authors.initials: P
authors.lastname: Bauer
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins; D005030:Ethylenes / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D007501:Iron / Q000378:metabolism*; D000090463:Iron Deficiencies; D007976:Leupeptins / Q000494:pharmacology; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010937:Plant Growth Regulators / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects; D060066:Protein Interaction Maps; D011993:Recombinant Fusion Proteins; D036226:Seedlings / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D059467:Transcriptome
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D005030:Ethylenes; D005998:Glycine; D007501:Iron; D007976:Leupeptins; D009687:Nuclear Proteins; D010937:Plant Growth Regulators; D046988:Proteasome Endopeptidase Complex; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C494589:EIL1 protein, Arabidopsis; C106987:EIN3 protein, Arabidopsis; C501411:FIT1 protein, Arabidopsis; C036216:ethylene; C088137:aminoethoxyvinylglycine; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde