title: α2-COP is involved in early secretory traffic in Arabidopsis and is required for plant growth.
abstract: COP (coat protein) I-coated vesicles mediate intra-Golgi transport and retrograde transport from the Golgi to the endoplasmic reticulum. These vesicles form through the action of the small GTPase ADP-ribosylation factor 1 (ARF1) and the COPI heptameric protein complex (coatomer), which consists of seven subunits (α-, β-, β'-, γ-, δ-, ε- and ζ-COP). In contrast to mammals and yeast, several isoforms for coatomer subunits, with the exception of γ and δ, have been identified in Arabidopsis. To understand the role of COPI proteins in plant biology, we have identified and characterized a loss-of-function mutant of α2-COP, an Arabidopsis α-COP isoform. The α2-cop mutant displayed defects in plant growth, including small rosettes, stems and roots and mislocalization of p24δ5, a protein of the p24 family containing a C-terminal dilysine motif involved in COPI binding. The α2-cop mutant also exhibited abnormal morphology of the Golgi apparatus. Global expression analysis of the α2-cop mutant revealed altered expression of plant cell wall-associated genes. In addition, a strong upregulation of SEC31A, which encodes a subunit of the COPII coat, was observed in the α2-cop mutant; this also occurs in a mutant of a gene upstream of COPI assembly, GNL1, which encodes an ARF-guanine nucleotide exchange factor (GEF). These findings suggest that loss of α2-COP affects the expression of secretory pathway genes.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universitat de València, Burjassot, Spain.
authors.forename: Fátima
authors.initials: F
authors.lastname: Gimeno-Ferrer
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universitat de València, Burjassot, Spain.|Estructura de Recerca Interdisciplinar en Biotecnología i Biomedicina (ERI BIOTECMED), Universitat de València, Burjassot, Spain.
authors.forename: Noelia
authors.initials: N
authors.lastname: Pastor-Cantizano
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universitat de València, Burjassot, Spain.|Estructura de Recerca Interdisciplinar en Biotecnología i Biomedicina (ERI BIOTECMED), Universitat de València, Burjassot, Spain.
authors.forename: César
authors.initials: C
authors.lastname: Bernat-Silvestre
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universitat de València, Burjassot, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Selvi-Martínez
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Vera-Sirera
authors.affiliation: School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Caiji
authors.initials: C
authors.lastname: Gao
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain.
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Perez-Amador
authors.affiliation: School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Liwen
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universitat de València, Burjassot, Spain.|Estructura de Recerca Interdisciplinar en Biotecnología i Biomedicina (ERI BIOTECMED), Universitat de València, Burjassot, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Aniento
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universitat de València, Burjassot, Spain.|Estructura de Recerca Interdisciplinar en Biotecnología i Biomedicina (ERI BIOTECMED), Universitat de València, Burjassot, Spain.
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Marcote
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001692:Biological Transport / Q000235:genetics; D020756:Coatomer Protein / Q000235:genetics* / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D020756:Coatomer Protein; C471983:AT2G32950 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases
keywords: Arabidopsis; COPI; COPII; Golgi apparatus; coat protein; p24 family protein; α1-COP; α2-COP; SEC31