title: Transcriptional and computational study of expansins differentially expressed in response to inclination in radiata pine.
abstract: Plants have the ability to reorient their vertical growth when exposed to inclination. This response can be as quick as 2 h in inclined young pine (Pinus radiata D. Don) seedlings, with over accumulation of lignin observed after 9 days s. Several studies have identified expansins involved in cell expansion among other developmental processes in plants. Six putative expansin genes were identified in cDNA libraries isolated from inclined pine stems. A differential transcript abundance was observed by qPCR analysis over a time course of inclination. Five genes changed their transcript accumulation in both stem sides in a spatial and temporal manner compared with non-inclined stem. To compare these expansin genes, and to suggest a possible mechanism of action at molecular level, the structures of the predicted proteins were built by comparative modeling methodology. An open groove on the surface of the proteins composed of conserved zresidues was observed. Using a cellulose polymer as ligand the protein-ligand interaction was evaluated, with the results showing differences in the protein-ligand interaction mode. Differences in the binding energy interaction can be explained by changes in some residues that generate differences in electrostatic surface in the open groove region, supporting the participation of six members of multifamily proteins in this specific process. The data suggests participation of different expansin proteins in the dissembling and remodeling of the complex cell wall matrix during the reorientation response to inclination.
authors.affiliation: Laboratorio de Fisiología Vegetal y Genética Molecular, Instituto de Ciencias Biológicas, Universidad de Talca, 2 Norte 685, Talca, Chile.
authors.forename: Patricio
authors.initials: P
authors.lastname: Mateluna
authors.affiliation: Laboratorio de Fisiología Vegetal y Genética Molecular, Instituto de Ciencias Biológicas, Universidad de Talca, 2 Norte 685, Talca, Chile.
authors.forename: Felipe
authors.initials: F
authors.lastname: Valenzuela-Riffo
authors.affiliation: Laboratorio de Fisiología Vegetal y Genética Molecular, Instituto de Ciencias Biológicas, Universidad de Talca, 2 Norte 685, Talca, Chile.
authors.forename: Luis
authors.initials: L
authors.lastname: Morales-Quintana
authors.affiliation: Laboratorio de Fisiología Vegetal y Genética Molecular, Instituto de Ciencias Biológicas, Universidad de Talca, 2 Norte 685, Talca, Chile.
authors.forename: Raúl
authors.initials: R
authors.lastname: Herrera
authors.affiliation: Laboratorio de Fisiología Vegetal y Genética Molecular, Instituto de Ciencias Biológicas, Universidad de Talca, 2 Norte 685, Talca, Chile. Electronic address: pramos@utalca.cl.
authors.forename: Patricio
authors.initials: P
authors.lastname: Ramos
mesh_terms: D000595:Amino Acid Sequence; D005786:Gene Expression Regulation; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D008954:Models, Biological; D008958:Models, Molecular; D010802:Phylogeny; D028223:Pinus / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D014158:Transcription, Genetic
chemical_list: D010940:Plant Proteins; C095825:expansin protein, plant
keywords: Cell wall remodeling; Expansin; Inclination stress; Molecular dynamics simulations; Molecular modeling; Pinus radiata