Characterization of a maize G‐box binding factor that is induced by hypoxia

Abstract

SummaryG-box cis-acting DNA sequence elements are present in the promoter region of a number of signal-inducible plant genes. In many cases this motif is essential for gene expression. Maize nuclear extracts contain a protein complex that binds specifically to the G-box sequence. Previously, a protein called GF14 was described that is physically associated with the G-box binding complex, but is not a DNA-binding factor in and of itself. This paper reports the isolation of a cDNA encoding a maize G-box binding factor (GBF). The deduced amino acid sequence indicates that maize GBF1 is a basic region-leucine zipper protein. GBF1 binds to the G-box element with specificity similar to that of the binding activity in nuclear extracts. Furthermore, maize GBF1 and the factor detected in nuclear extract are identical in their molecular weight and are immunologicelly related. GBF1 mRNA accumulates rapidly in hypoxicelly induced maize cells prior to the increase in Adhl mRNA levels. Taken together with results that indicate that GBF1 binds to the hypoxia-responsive promoter of maize Adh 1, these observations suggest that GBF1 may be one of the factors involved in the activation of Adh l.

The Product of the Rice myb7 Unspliced mRNA Dimerizes with the Maize Leucine Zipper Opaque2 and Stimulates Its Activity in a Transient Expression Assay

“…These data suggest that post-transcriptional regulation controls the ratio between myb7 unspliced and spliced forms (7). This hypothesis is supported by the observation that the 5Ј region of the first intron can direct the synthesis of an in-frame leucine zipper, a functional domain present in several transcription factors (15)(16)(17)(18).…”

Identification and characterization of GIP1, an Arabidopsis thaliana protein that enhances the DNA binding affinity and reduces the oligomeric state of G-box binding factors

“…The coding region for maize GBF1 [11] was fused to the Cterminal GAL4 DNA binding domain of the yeast two-hybrid binding vector pGBT9. The vector, pET15b GBF1, was used as a template in a PCR with the primers 5'-GAG GAT CCA GGC TCA GGA TGA-3' and 3'-GCT AGT TAT TGC TCA GCG G-5' to generate a BamHI GBF1 cassette.…”

“…Self-activation studies and protein extraction experiments were also performed as per the manufacturer's instructions. Western analysis of yeast extracts with anti-GBF1 antibodies was performed as described previously [11]. All procedures used for library screening with the A. thaliana Matchmaker cDNA library (Clontech) were done in accordance with the manufacturers' protocols.…”

“…The expression vector and methods for the production of maize GBF1 (ZmGBF1) were as previously described [11]. The expression vectors and methods for the production of A. thaliana GBF3a (AtGBF3a) and GBF3b (AtGBF3b) were as previously described [13].…”

HALF‐1, a bZIP‐type protein, interacting with the wheat transcription factor HBP‐1a contains a novel transcriptional activation domain

“…A large number of bZIP-type proteins have also been identified in plants Meier & Gruissem 1994;Menkens & Cashmore 1994;Mikami et al 1994;Niu & Guiltinan 1994;de Vetten & Ferl 1995; for review see Foster et al 1994). An interesting feature shared by these plant bZIP-type proteins is that they direct binding to nucleotide sequences with the ACGT core, although affinity is strongly influenced by the flanking sequences.…”