title: A nuclear gene encoding the iron-sulfur subunit of mitochondrial complex II is regulated by B3 domain transcription factors during seed development in Arabidopsis.
abstract: Mitochondrial complex II (succinate dehydrogenase) is part of the tricarboxylic acid cycle and the respiratory chain. Three nuclear genes encode its essential iron-sulfur subunit in Arabidopsis (Arabidopsis thaliana). One of them, SUCCINATE DEHYDROGENASE2-3 (SDH2-3), is specifically expressed in the embryo during seed maturation, suggesting that SDH2-3 may have a role as the complex II iron-sulfur subunit during embryo maturation and/or germination. Here, we present data demonstrating that three abscisic acid-responsive elements and one RY-like enhancer element, present in the SDH2-3 promoter, are involved in embryo-specific SDH2-3 transcriptional regulation. Furthermore, we show that ABSCISIC ACID INSENSITIVE3 (ABI3), FUSCA3 (FUS3), and LEAFY COTYLEDON2, three key B3 domain transcription factors involved in gene expression during seed maturation, control SDH2-3 expression. Whereas ABI3 and FUS3 interact with the RY element in the SDH2-3 promoter, the abscisic acid-responsive elements are shown to be a target for bZIP53, a member of the basic leucine zipper (bZIP) family of transcription factors. We show that group S1 bZIP53 protein binds the promoter as a heterodimer with group C bZIP10 or bZIP25. To the best of our knowledge, the SDH2-3 promoter is the first embryo-specific promoter characterized for a mitochondrial respiratory complex protein. Characterization of succinate dehydrogenase activity in embryos from two homozygous sdh2-3 mutant lines permits us to conclude that SDH2-3 is the major iron-sulfur subunit of mature embryo complex II. Finally, the absence of SDH2-3 in mutant seeds slows down their germination, pointing to a role of SDH2-3-containing complex II at an early step of germination.
authors.affiliation: Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Hannetz
authors.initials: H
authors.lastname: Roschzttardtz
authors.forename: Ignacia
authors.initials: I
authors.lastname: Fuentes
authors.forename: Marcos
authors.initials: M
authors.lastname: Vásquez
authors.forename: Claudia
authors.initials: C
authors.lastname: Corvalán
authors.forename: Gabriel
authors.initials: G
authors.lastname: León
authors.forename: Isabel
authors.initials: I
authors.lastname: Gómez
authors.forename: Alejandro
authors.initials: A
authors.lastname: Araya
authors.forename: Loreto
authors.initials: L
authors.lastname: Holuigue
authors.forename: Jesús
authors.initials: J
authors.lastname: Vicente-Carbajosa
authors.forename: Xavier
authors.initials: X
authors.lastname: Jordana
mesh_terms: D017360:Arabidopsis / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D001483:Base Sequence; D001665:Binding Sites; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000235:genetics; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D013385:Succinate Dehydrogenase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000502:physiology*
chemical_list: C091601:ABI3 protein, Arabidopsis; D029681:Arabidopsis Proteins; C502726:FUSCA3 protein, Arabidopsis; D007506:Iron-Sulfur Proteins; C504240:LEC2 protein, Arabidopsis; D021122:Protein Subunits; C496080:SDH2-3 protein, Arabidopsis; D014157:Transcription Factors; D013385:Succinate Dehydrogenase