title: A novel abscisic acid- and dehydration-responsive gene family from the resurrection plant Craterostigma plantagineum encodes a plastid-targeted protein with DNA-binding activity.
abstract: In the desiccation-tolerant resurrection plant Craterostigma plantagineum Hochst. the chloroplasts undergo major ultrastructural changes during dehydration, which are reversible upon rehydration. Such alterations argue the need for efficient protective/stabilising mechanisms to exist. Here we describe a novel gene family that is rapidly and transiently expressed in response to both dehydration and exogenously applied abscisic acid, mostly in the chloroplast-rich palisade layer on the adaxial side of the leaf. Analysis of the putative coding region suggests that the resulting protein is plastid-targeted. This was confirmed using a chimeric green fluorescent protein (GFP) reporter construct in transgenic tobacco plants - hence the gene family is termed Plastid Targeted Protein ( CpPTP). Fluorescence microscopy also revealed that CpPTP was localised in structures similar to proplastid nucleoids in transgenic tobacco ( Nicotiana tabacum L.) BY-2 cells. The ability of CpPTP to interact with DNA was demonstrated through a DNaseI protection assay. A structure-prediction programme suggests that the mature CpPTP is composed almost entirely of a pattern of hydrophobic and hydrophilic residues that form heptad repeats, which are the hallmarks of a coiled-coil domain. Given the localisation and DNA-binding property of the protein, we propose that CpPTP plays a role during the early stages of dehydration-induced chloroplast remodelling.
authors.affiliation: Max-Planck-Institut für Züchtungsforshung Carl-von-Linné Weg 10, 50829 Köln, Germany.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Phillips
authors.forename: Tobias
authors.initials: T
authors.lastname: Hilbricht
authors.forename: Francesco
authors.initials: F
authors.lastname: Salamini
authors.forename: Dorothea
authors.initials: D
authors.lastname: Bartels
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D000595:Amino Acid Sequence; D001692:Biological Transport; D002736:Chloroplasts / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D049452:Green Fluorescent Proteins; D017403:In Situ Hybridization; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D019684:Magnoliopsida / Q000187:drug effects / Q000235:genetics*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D005810:Multigene Family; D018515:Plant Leaves / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000166:cytology / Q000235:genetics; D014867:Water / Q000494:pharmacology* / Q000502:physiology
chemical_list: C107112:CDT-1 protein, Craterostigma plantagineum; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D008164:Luminescent Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D014867:Water; D049452:Green Fluorescent Proteins; D000040:Abscisic Acid