CpR18, a novel SAP-domain plant transcription factor, binds to a promoter region necessary for ABA mediated expression of the CDeT27-45 gene from the resurrection plant Craterostigma plantagineum Hochst

CDeT27-45 is a lea -like gene from the resurrection plant Craterostigma plantagineum (Scrophulariaceae) which is strongly expressed in vegetative tissues in response to dehydration or treatment with abscisic acid (ABA). Expression of the gene is correlated with the acquisition of desiccation tolerance. Nuclear proteins bind to a 29-bp cis -regulatory region of the promoter which is essential for transcriptional activation of the CDeT27-45 gene by ABA. Using a yeast one-hybrid screen, the cDNA clone CpR18 was isolated, which encodes a protein with specific binding activity for the cis -regulatory element in the CDeT27-45 promoter. The protein contains an acidic region, a SAP-domain, a zinc finger of the C-3 H-type, and two motifs which are conserved in proteins from several plant species. One of the conserved regions is rich in basic residues and is predicted to form a helix-loop-helix structure. The R18 gene shows high similarities to genomic sequences and ESTs from other plant species. The tissue-specific expression pattern of the rare R18 mRNA and the distribution of nuclear protein binding activity for the CDeT27-45 promoter fragment are compared. The R18 protein is indeed localized in the nucleus, and activates transcription of CDeT27-45 promoter-GUS fusion constructs in tobacco protoplasts. DNA blot analysis and isolation of genomic clones reveal that two copies of R18 are present in the C. plantagineum genome

CpR18, a novel SAP-domain plant transcription factor, binds to a promoter region necessary for ABA mediated expression of the CdeT27-45 gene from the resurrection plant Craterostigma plantagineum Hochst.

CDeT27-45 is a lea -like gene from the resurrection plant Craterostigma plantagineum (Scrophulariaceae) which is strongly expressed in vegetative tissues in response to dehydration or treatment with abscisic acid (ABA). Expression of the gene is correlated with the acquisition of desiccation tolerance. Nuclear proteins bind to a 29-bp cis -regulatory region of the promoter which is essential for transcriptional activation of the CDeT27-45 gene by ABA. Using a yeast one-hybrid screen, the cDNA clone CpR18 was isolated, which encodes a protein with specific binding activity for the cis -regulatory element in the CDeT27-45 promoter. The protein contains an acidic region, a SAP-domain, a zinc finger of the C-3 H-type, and two motifs which are conserved in proteins from several plant species. One of the conserved regions is rich in basic residues and is predicted to form a helix-loop-helix structure. The R18 gene shows high similarities to genomic sequences and ESTs from other plant species. The tissue-specific expression pattern of the rare R18 mRNA and the distribution of nuclear protein binding activity for the CDeT27-45 promoter fragment are compared. The R18 protein is indeed localized in the nucleus, and activates transcription of CDeT27-45 promoter-GUS fusion constructs in tobacco protoplasts. DNA blot analysis and isolation of genomic clones reveal that two copies of R18 are present in the C. plantagineum genome

Evaluation de l'état parodontal de patients sous traitement par la méthadone

STRASBOURG-Medecine (674822101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

A novel abscisic acid and dehydration responsive gene family from the resurrection plant Craterostigma plantagineum encodes a plastid targeted protein with a coiled-coil domain.

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 nucleoides 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

Retrotransposons and siRNA have a role in the evolution of desiccation tolerance leading to resurrection of the plant Craterostigma plantagineum

\u2022 Craterostigma plantagineum can lose up to 96% of its water content but fullyrecover within hours after rehydration. The callus tissue of the plant becomesdesiccation tolerant upon pre-incubation with abscisic acid (ABA). In callus andvegetative organs, ABA addition and water depletion induce a set of dehydrationresponsivegenes.\u2022 Previously, activation tagging led to the isolation of Craterostigma desiccationtolerant (CDT-1), a dehydration-related ABA-inducible gene which renders callusdesiccation tolerant without ABA pre-treatment. This gene belongs to a family ofretroelements, members of which are inducible by dehydration.\u2022 Craterostigma plantagineum transformation with mutated versions of CDT-1indicated that protein is not required for the induction of callus desiccation tolerance.Northern analysis and protoplast transfection indicated that CDT-1 directs thesynthesis of a double-stranded 21-bp short interfering RNA (siRNA), which opensthe metabolic pathway for desiccation tolerance.\u2022 Via transposition, these retroelements have progressively increased the capacity ofthe species to synthesize siRNA and thus recover after dehydration. This may be a caseof evolution towards the acquisition of a new trait, stimulated by the environmentacting directly on intra-genomic DNA replication