The trihelix DNA-binding motif in higher plants is not restricted to the transcription factors GT-1 and GT-2.
GT-2 is a plant transcriptional activator that contains two separate, but similar, trihelix DNA-binding domains. GT-1 is similar to GT-2, although it contains only one of such domains. cDNAs that encode GT-2 were isolated from rice (OS-GT2) and Arabidopsis (AT-GT2). Evidence is presented for the existence of an Arabidopsis gene family that is structurally related to AT-GT2. Two members of this GT2-like family, AT-GTL1 and AT-GTL2, have been isolated and characterized. Their sequences suggest that they evolved by a recent gene duplication event. Both AT-GT2 and AT-GTL genes contain an intron in the amino-terminal trihelix motif, indicating that this DNA-binding domain resulted from exon shuffling. RNA gel blot analysis using AT-GTL1 as a probe revealed four transcripts in the aerial part of the plant. All mRNA levels were significantly higher in siliques, suggesting that this gene family may function in fruit and/or seed development. To date, DNA-binding proteins characterized by the trihelix motif have been described only in plants, and may therefore be involved in plant-specific processes. Our results show that in Arabidopsis thaliana, the trihelix motif is not restricted to the GT-1 and GT-2 DNA-binding proteins.
Smalle
J
J
Laboratorium voor Genetica, Departement Genetica, Vlaams Interuniversitair Instituut voor Biotechnologie, Universiteit Gent, K. L. Ledeganckstraat 35, B-9000 Gent, Belgium.
Kurepa
J
J
Haegman
M
M
Gielen
J
J
Van Montagu
M
M
Van Der Straeten
D
D
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D017343:Genes, Plant; D015698:Genomic Library; D008957:Models, Genetic; D008969:Molecular Sequence Data; D005810:Multigene Family; D010940:Plant Proteins / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D012333:RNA, Messenger / Q000032:analysis; D018749:RNA, Plant / Q000032:analysis; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C083955:GT2 protein, Arabidopsis; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant