title: Iron sensors and signals in response to iron deficiency.
abstract: The transcription of genes involved in iron acquisition in plants is induced under iron deficiency, but our understanding of iron sensors and signals remains limited. Iron Deficiency-responsive Element-binding Factor 1 (IDEF1) and Hemerythrin motif-containing Really Interesting New Gene- and Zinc-finger proteins (HRZs)/BRUTUS (BTS) have recently emerged as candidate iron sensors because of their functions as potent regulators of iron deficiency responses and their iron-binding properties. IDEF1 is a central transcriptional regulator of graminaceous genes involved in iron uptake and utilization, predominantly during the early stages of iron deficiency. HRZs/BTS are E3 ubiquitin ligases and negative regulators of iron deficiency responses in both graminaceous and non-graminaceous plants. Rice OsHRZ1 and OsHRZ2 are also potent regulators of iron accumulation. Characterizing these putative iron sensors also provides clues to understanding the nature of iron signals, which may involve ionized iron itself, other metals, oxygen, redox status, heme and iron-sulfur clusters, in addition to metabolites affected by iron deficiency. Systemic iron responses may also be regulated by phloem-mobile iron and its chelators such as nicotianamine. Iron sensors and signals will be identified by demonstration of signal transmission by IDEF1, HRZs/BTS, or unknown factors.
authors.affiliation: Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan; Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan. Electronic address: abkoba@ishikawa-pu.ac.jp.
authors.forename: Takanori
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan. Electronic address: annaoko@mail.ecc.u-tokyo.ac.jp.
authors.forename: Naoko K
authors.initials: NK
authors.lastname: Nishizawa
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007501:Iron / Q000378:metabolism; D000090463:Iron Deficiencies; D035925:Iron-Regulatory Proteins / Q000235:genetics* / Q000378:metabolism; D012275:Oryza / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D015398:Signal Transduction; D013312:Stress, Physiological / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism
chemical_list: D035925:Iron-Regulatory Proteins; D010940:Plant Proteins; D014157:Transcription Factors; D007501:Iron; D044767:Ubiquitin-Protein Ligases
keywords: HRZs/BTS; IDEF1; Iron deficiency; Sensor; Signaling