title: The Unstructured N-terminal Region of Arabidopsis Group 4 Late Embryogenesis Abundant (LEA) Proteins Is Required for Folding and for Chaperone-like Activity under Water Deficit.
abstract: Late embryogenesis abundant (LEA) proteins are a conserved group of proteins widely distributed in the plant kingdom that participate in the tolerance to water deficit of different plant species. In silico analyses indicate that most LEA proteins are structurally disordered. The structural plasticity of these proteins opens the question of whether water deficit modulates their conformation and whether these possible changes are related to their function. In this work, we characterized the secondary structure of Arabidopsis group 4 LEA proteins. We found that they are disordered in aqueous solution, with high intrinsic potential to fold into α-helix. We demonstrate that complete dehydration is not required for these proteins to sample ordered structures because milder water deficit and macromolecular crowding induce high α-helix levels in vitro, suggesting that prevalent conditions under water deficit modulate their conformation. We also show that the N-terminal region, conserved across all group 4 LEA proteins, is necessary and sufficient for conformational transitions and that their protective function is confined to this region, suggesting that folding into α-helix is required for chaperone-like activity under water limitation. We propose that these proteins can exist as different conformers, favoring functional diversity, a moonlighting property arising from their structural dynamics.
authors.affiliation: From the Departamentos de Biología Molecular de Plantas and.
authors.forename: Cesar L
authors.initials: CL
authors.lastname: Cuevas-Velazquez
authors.affiliation: Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, 62250 Cuernavaca, México.
authors.forename: Gloria
authors.initials: G
authors.lastname: Saab-Rincón
authors.affiliation: From the Departamentos de Biología Molecular de Plantas and.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Reyes
authors.affiliation: From the Departamentos de Biología Molecular de Plantas and crobles@ibt.unam.mx.
authors.forename: Alejandra A
authors.initials: AA
authors.lastname: Covarrubias
mesh_terms: D017360:Arabidopsis / Q000737:chemistry* / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D010940:Plant Proteins
keywords: Arabidopsis thaliana; intrinsically disordered protein; plant molecular biology; protein folding; protein structure; stress response