title: Characterization of promoter elements required for expression and induction by sucrose of the Arabidopsis COX5b-1 nuclear gene, encoding the zinc-binding subunit of cytochrome c oxidase.
abstract: Arabidopsis COX5b-1 encodes an isoform of the zinc binding subunit 5b of mitochondrial cytochrome c oxidase. A promoter region required for expression and induction by sucrose of this gene was analyzed using plants stably transformed with mutagenized promoter fragments fused to the gus reporter gene. Promoter dependent expression is absolutely dependent on a G-box present at -228 from the translation start site. This element interacts in vitro and in vivo with transcription factors from the bZip family, preferentially with the abscisic acid-responsive element binding factor AREB2/ABF4. A region located upstream of the G-box (-333/-259) contains elements with the core sequence ATCATT and distalB-like sequences (CCACTTG) that are required for expression in vegetative tissues. These sequences bind different sets of proteins present in plant nuclear extracts and participate in induction by sucrose (ATCATT) and abscisic acid (distalB) of the COX5b-1 promoter. We propose that the COX5b-1 promoter has acquired novel regulatory mechanisms during evolution after gene duplication. These novel mechanisms have allowed the diversification of expression patterns, but also the conservation of some responses that, as induction by sucrose, are shared by COX5b-1 and other genes encoding components of the mitochondrial respiratory chain. Conservation of these responses may be a pre-requisite for the successful incorporation of new regulatory elements in this class of genes.
authors.affiliation: Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, CC 242 Paraje El Pozo, 3000 Santa Fe, Argentina.
authors.forename: Raúl N
authors.initials: RN
authors.lastname: Comelli
authors.forename: Ivana L
authors.initials: IL
authors.lastname: Viola
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Gonzalez
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics*; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics*; D024202:Electrophoretic Mobility Shift Assay; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013395:Sucrose / Q000494:pharmacology*; D020798:Two-Hybrid System Techniques; D015032:Zinc / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D009687:Nuclear Proteins; D010937:Plant Growth Regulators; D011993:Recombinant Fusion Proteins; D013395:Sucrose; D000040:Abscisic Acid; D003576:Electron Transport Complex IV; D005966:Glucuronidase; D015032:Zinc