Reference "Molecular analysis of three maize 22 kDa auxin-binding protein genes--transient promoter expression and regulatory regions"

Reference ID

7086

Title

Molecular analysis of three maize 22 kDa auxin-binding protein genes--transient promoter expression and regulatory regions

Source

The Plant journal : for cell and molecular biology, 1993, vol. 4, pp. 423-432

Authors (8)

Schwob-E	Choi-S-Y
Simmons-C	Migliaccio-F
Ilag-L	Hesse-T
Palme-K	Soll-D

Abstract

The site I 22 kDa auxin-binding proteins from maize are encoded by a small gene
family comprising at least five members. Here the cloning and molecular analysis
of the Zm-ERabp1, Zm-ERabp4, and Zm-ERabp5 genes is presented. All three encode
22-23 kDa proteins displaying a transit peptide, a C-terminal KDEL sequence, as
well as glycosylation and auxin-binding sites. The Zm-ERabp4 and Zm-ERabp5 genes
are very similar. The Zm-ERabp1 gene encodes a related protein, but its
promoter, leader and signal peptide are very different. Northern analysis using
gene-specific oligonucleotide probes indicates that Zm-ERabp4 is expressed in
leaves and coleoptiles but weakly in roots, whereas Zm-ERabp5 expression is
barely detectable in these tissues. RNA-PCR indicated that all three genes are
none the less expressed in many tissues. Primer-extension analysis revealed an
unusually long (320 bases) Zm-ERabp1 leader containing an 80 codon ORF which, if
expressed, would encode a positively charged protein with some similarity to
transcription factors. In a transient promoter-reporter gene expression system
using maize leaf protoplasts the Zm-ERabp1 promoter is more active than the Zm-
ERabp4 and Zm-ERabp5 promoters. Promoter deletion analysis of Zm-ERabp1 has
identified a negative regulatory sequence in a region from -364 bp and -130 bp,
deletion of which results in about twofold higher expression. This region
contains both enhancer- and G-box-related sequences. Deletion of -126 bp to +64
bp, which contains the TATA box and transcription start, results in a large
decrease in expression.