title: Phylogenetic and functional analysis of Arabidopsis RCI2 genes.
abstract: Six new Arabidopsis thaliana genes (AtRCI2C-H) have been identified that show high homology to AtRCI2A and AtRCI2B. Sequence comparisons revealed that AtRCI2-related genes are widely spread among very different organisms, including other plant species, prokaryotes, fungi, and simply organized animals, and are also organized in gene families. Most RCI2 genes show a similar exon-intron organization, which indicates that they have been structurally conserved during evolution, and encode small, highly hydrophobic proteins containing two putative transmembrane domains. Consistently, the majority of AtRCI2 proteins localize in the plasma membrane. RCI2 proteins exhibit an elevated level of sequence similarity and seem to have evolved from a common ancestor. In spite of their high similarity, conserved subcellular localization, and common origin, experimental evidence is presented suggesting that different RCI2 proteins may have distinct functional roles. Thus, as previously demonstrated for AtRCI2A and AtRCI2B, the newly identified AtRCI2 genes (AtRCI2C-H) are differentially regulated in Arabidopsis organs and in response to abiotic stresses and ABA treatment. Furthermore, only the AtRCI2 proteins that do not contain the C-terminal hydrophilic tail (i.e. AtRCI2A-C and AtRCI2H) are able to complement for the loss of the yeast AtRCI2-related gene PMP3. On the basis of these results, different aspects on the evolution and roles of RCI2 genes are discussed.
authors.affiliation: Departamento de Biotecnología, Instituto Nacional de Investigación y Tecnología Agraría y Alimentaria (INIA), Carretera de la Coruña, Km. 7, 28040 Madrid, Spain.
authors.forename: Joaquín
authors.initials: J
authors.lastname: Medina
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Ballesteros
authors.forename: Julio
authors.initials: J
authors.lastname: Salinas
mesh_terms: D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D017173:Caenorhabditis elegans / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism; D017124:Conserved Sequence; D005816:Genetic Complementation Test; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D012275:Oryza / Q000235:genetics; D010802:Phylogeny; D011510:Proteolipids / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; C410735:PMP3 protein, S cerevisiae; D011510:Proteolipids; C108982:RCI2A protein, Arabidopsis; C424721:RCI2B protein, Arabidopsis; D029701:Saccharomyces cerevisiae Proteins