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

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

^*Center for Molecular Biology and Genetics and ^†Department of Bioresources, Mie University, 1515 Kamihama-cho, Tsu 514-8507, Japan

Communicated by Bernard O. Phinney, University of California, Los Angeles, CA (received for review August 17, 1999)

Abstract

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.

Footnotes

↵ ‡ To whom reprint requests should be addressed at the * address. E-mail: hattori{at}gene.recs.mie-u.ac.jp.
Data deposition: The sequence reported in this paper has been deposited in the GenBank database (accession no. AB023288).
Abbreviations:

ABA,

abscisic acid;

ABRE,

abscisic acid response element;

ABRC,

ABA responsive cis-element complex;

bZIP,

basic region leucine zipper;

GAD,

GAL4 activation domain;

GUS,

β-glucuronidase;

GBD,

GAL4 DNA-binding domain