title: Iron-binding haemerythrin RING ubiquitin ligases regulate plant iron responses and accumulation.
abstract: Iron is essential for most living organisms. Plants transcriptionally induce genes involved in iron acquisition under conditions of low iron availability, but the nature of the deficiency signal and its sensors are unknown. Here we report the identification of new iron regulators in rice, designated Oryza sativa Haemerythrin motif-containing Really Interesting New Gene (RING)- and Zinc-finger protein 1 (OsHRZ1) and OsHRZ2. OsHRZ1, OsHRZ2 and their Arabidopsis homologue BRUTUS bind iron and zinc, and possess ubiquitination activity. OsHRZ1 and OsHRZ2 are susceptible to degradation in roots irrespective of iron conditions. OsHRZ-knockdown plants exhibit substantial tolerance to iron deficiency, and accumulate more iron in their shoots and grains irrespective of soil iron conditions. The expression of iron deficiency-inducible genes involved in iron utilization is enhanced in OsHRZ-knockdown plants, mostly under iron-sufficient conditions. These results suggest that OsHRZ1 and OsHRZ2 are iron-binding sensors that negatively regulate iron acquisition under conditions of iron sufficiency.
authors.affiliation: 1] Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan [2] Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi, Ishikawa 921-8836, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Seiji
authors.initials: S
authors.lastname: Nagasaka
authors.forename: Takeshi
authors.initials: T
authors.lastname: Senoura
authors.forename: Reiko Nakanishi
authors.initials: RN
authors.lastname: Itai
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nakanishi
authors.forename: Naoko K
authors.initials: NK
authors.lastname: Nishizawa
mesh_terms: D055785:Gene Knockdown Techniques; D007501:Iron / Q000378:metabolism*; D012275:Oryza / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000201:enzymology / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000235:genetics; D015032:Zinc / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D007501:Iron; D044767:Ubiquitin-Protein Ligases; D015032:Zinc