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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
Author(s) -
Hilbricht Tobias,
Salamini Francesco,
Bartels Dorothea
Publication year - 2002
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2002.01357.x
Subject(s) - biology , gene , promoter , transcription factor , gene expression , zinc finger , microbiology and biotechnology , genetics , fusion protein , recombinant dna
Summary 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.