GeBP Transcription Factor Family
Trichomes of Arabidopsis are single-celled epidermal hair that are a useful model for
studying plant cell fate determination. Trichome initiation requires the activity of
the GLABROUS1 (GL1) gene whose expression in epidermal and trichome cells is dependent
on the presence of a 3'-cis-regulatory element. Using a one-hybrid screen, we have
isolated a cDNA, which encodes for a protein, GL1 enhancer binding protein (GeBP), that
binds this regulatory element in yeast and in vitro. GeBP and its three homologues in
Arabidopsis share two regions: a central region with no known motifs and a C-terminal
region with a putative leucine-zipper motif. We show that both regions are necessary
for trans-activation in yeast. A translational fusion with the Yellow Fluorescent
Protein (YFP) indicates that GeBP is a nuclear protein whose localization is restricted
to, on average, 3-5 subnuclear foci that might correspond to nucleoli. Transcriptional
fusion with the GUS reporter indicates that GeBP is mainly expressed in vegetative
meristematic tissues and in very young leaf primordia. We looked at GeBP expression in
plants mutated in or misexpressing KNAT1, a KNOX gene, expressed in the shoot apical
meristem and downregulated in leaf founder cells, and found that GeBP transcript level
is regulated by KNAT1 suggesting that KNAT1 is a transcriptional activator of GeBP.
This regulation suggests that GeBP is acting as a repressor of leaf cell fate.
16 predicted putative GeBP TF peptide,
CDS, and cDNA sequences,
blast HSP, and gene level multiple sequence alignment in
Soy - TFKB.
DUF573 domain peptide sequences and alignment
and phylogeny tree.
5 GeBP protein
and DNA
sequences with
annotations for soybean in PlantTFDB. All are partial sequences.
Last updated by Dr. Jeff Chen
on July 15, 2009.
