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A bZIP factor, TRAB1, interacts with VP1 and mediates abscisic acid-induced transcription

Hobo, T., Kowyama, Y., Hattori, T.
Proceedings of the National Academy of Sciences of the United States of America 1999 v.96 no.26 pp. 15348-15353
Oryza sativa, transcription factors, regulatory sequences, recombinant DNA, reporter genes, beta-glucuronidase, gene expression, abscisic acid, transgenic plants, protoplasts, nucleotide sequences, complementary DNA, embryo (plant), leaves, roots, messenger RNA, promoter regions, transcription (genetics), binding sites
The transcription factor VP1 regulates maturation and dormancy in plant seeds by activating genes responsive to the stress hormone abscisic acid (ABA). Although activation involves ABA-responsive elements (ABREs), VP1 itself does not specifically bind ABREs. Instead, we have identified and cloned a basic region leucine zipper (bZIP) factor, TRAB1, that interacts with both VP1 and ABREs. Transcription from a chimeric promoter with GAL4-binding sites was ABA-inducible if cells expressed a GAL4 DNA-binding domain::TRAB1 fusion protein. Results indicate that TRAB1 is a true trans-acting factor involved in ABA-regulated transcription and reveal a molecular mechanism for the VP1-dependent, ABA-inducible transcription that controls maturation and dormancy in plant embryos.