BASIC PENTACYSTEINE1, a GA Binding Protein That Induces Conformational Changes in the Regulatory Region of the Homeotic Arabidopsis Gene SEEDSTICK

Abstract

The mechanisms for the regulation of homeotic genes are poorly understood in most organisms, including plants. We identified BASIC PENTACYSTEINE1 (BPC1) as a regulator of the homeotic Arabidopsis thaliana gene SEEDSTICK (STK), which controls ovule identity, and characterized its mechanism of action. A combination of tethered particle motion analysis and electromobility shift assays revealed that BPC1 is able to induce conformational changes by cooperative binding to purine-rich elements present in the STK regulatory sequence. Analysis of STK expression in the bpc1 mutant showed that STK is upregulated. Our results give insight into the regulation of gene expression in plants and provide the basis for further studies to understand the mechanisms that control ovule identity in Arabidopsis.

BASIC PENTACYSTEINE Proteins Mediate MADS Domain Complex Binding to the DNA for Tissue-Specific Expression of Target Genes in Arabidopsis

“…Electrophoretic mobility shift assay (EMSA) experiments using primers based on the STK promoter sequence predicted that BPC1 binds to seven out of 12 GAGA boxes (Kooiker et al, 2005). Based on these experiments, the RGARAGRRA consensus BPC1 binding sequence (consensus [C]-box) was proposed.…”

“…These NC-boxes did not bind BPC1 in EMSA studies (Kooiker et al, 2005). We carefully reanalyzed the STK promoter region and discovered the presence of five additional NC-boxes (see Supplemental Figure 1 …”

“…Its cooperative binding was shown to induce conformational changes in the STK regulatory region, suggesting that multiple consensus sites are required for the regulation of STK. Furthermore, it was shown that STK expression was upregulated in the bpc1-1 single mutant, although the spatial expression profile of STK was not changed (Kooiker et al, 2005).…”

“…Recently, we identified BPC1 as a regulator of the ovule identity gene SEEDSTICK (STK), which is specifically expressed in ovules (Rounsley et al, 1995;Pinyopich et al, 2003;Brambilla et al, 2007). BPC1 binds to the STK promoter at multiple guanine and adenine (GA)-rich boxes, which have the RGARAGRRA consensus sequence (Kooiker et al, 2005). Its cooperative binding was shown to induce conformational changes in the STK regulatory region, suggesting that multiple consensus sites are required for the regulation of STK.…”

Methods for Development of Microsatellite Markers: An Overview

“…The over-representation of CT/GA and CTT/GAA repeats in the 5'-flanks of Arabidopsis thaliana suggest their potential involvement in regulating gene expression . The (GA)n repeats in promoters govern the regulation of certain plant genes (Meister et al, 2004) and exhibit protein-binding affinity (Kooiker et al, 2005). The CT/GA repeat variation in the 5′ UTR of the waxy gene is correlated with amylose content in rice (Bao et al, 2002).…”