Gene regulation during late embryogenesis: the RY motif of maturation‐specific gene promoters is a direct target of the FUS3 gene product

Abstract

SummaryThe Arabidopsis mutants fus3 and abi3 show pleiotropic effects during embryogenesis including reduced levels of transcripts encoding embryo-speci®c seed proteins. To investigate the interaction between the B3-domain-containing transcription factors FUS3 and ABI3 with the RY cis-motif, conserved in many seed-speci®c promoters, a promoter analysis as well as band-shift experiments were performed. The analysis of promoter mutants revealed the structural requirements for the function of the RY ciselement. It is shown that both the nucleotide sequence and the alternation of purin and pyrimidin nucleotides (RY character) are essential for the activity of the motif. Further, it was shown that FUS3 and ABI3 can act independently of each other in controlling promoter activity and that the RY cis-motif is a target for both transcription factors. For FUS3, which is so far the smallest known member of the B3-domain family, a physical interaction with the RY motif was established. The functional and biochemical data demonstrate that the regulators FUS3 and ABI3 are essential components of a regulatory network acting in concert through the RY-promoter element to control gene expression during late embryogenesis and seed development.

A Nuclear Gene Encoding the Iron-Sulfur Subunit of Mitochondrial Complex II Is Regulated by B3 Domain Transcription Factors during Seed Development in Arabidopsis

“…Accordingly, we found that FUS3 is able to specifically bind the RY element of the SDH2-3 promoter in EMSA assays (Fig. 6A), in agreement with observations made on the Vicia faba legumin and the Arabidopsis At2S3 albumin promoters (Reidt et al, 2000;Kroj et al, 2003). Only using a more sensitive ELISA method have we also shown that ABI3 interacts directly with a probe containing the RY element (Fig.…”

“…Recent studies have demonstrated that they directly controlled the induction of SSP gene expression, recognizing the RY motifs present in the promoters of these target genes Reidt et al, 2000;Kroj et al, 2003;Mö nke et al, 2004;Braybrook et al, 2006). Accordingly, we found that FUS3 is able to specifically bind the RY element of the SDH2-3 promoter in EMSA assays (Fig.…”

“…Since ABRE2 mutation almost abolishes GUS expression, this element appears to be the most important by itself. Considering that the mutations introduced in ABRE and RY boxes have been shown to abolish the binding of bZIP and B3 domain transcription factors, respectively (Reidt et al, 2000;Bensmihen et al, 2002), these results suggest that transcription factors from these families may be directly involved in SDH2-3 regulation. .…”

“…FUS3 and ABI3 Bind the SDH2-3 Promoter RY motifs are putative targets for B3 domain transcription factors (Suzuki et al, 1997;Reidt et al, 2000;Kroj et al, 2003;Mö nke et al, 2004). To investigate whether these factors could recognize in vitro the SDH2-3 RY promoter element, ABI3 and FUS3 proteins expressed in Escherichia coli were tested for their ability to bind to an oligonucleotide containing this element in an electrophoretic mobility shift assay (EMSA).…”

Role of Abscisic Acid in Seed Dormancy

“…FUS3 and LEC1 modulate the abundance of ABI3 protein in seeds, and synergistic interactions between the three proteins (ABI3, FUS3, and LEC1) are thought to control various key events, including accumulation of chlorophyll and anthocyanins, sensitivity to ABA, and expression of individual members of the 12S storage protein gene family (Parcy and others 1997). In transient transcription assays, FUS3 activates the transcription of maturation-specific genes containing the RY motif (Reidt and others 2000). Thus, both FUS3 and ABI3 may be essential components of a regulatory network acting in concert through the RY-promoter element to control gene expression during late embryogenesis and seed development.…”