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 C3H-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.
Hilbricht
Tobias
T
Max-Planck-Institut für Züchtungsforschung, Carl-von-Linné-Weg 10, D-50829 Köln, Germany.
Salamini
Francesco
F
Bartels
Dorothea
D
D000040:Abscisic Acid / Q000494:pharmacology*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D032181:Craterostigma / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003890:Desiccation; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics*; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D005810:Multigene Family; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000235:genetics; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D010940:Plant Proteins; D018749:RNA, Plant; D014157:Transcription Factors; D000040:Abscisic Acid