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

Abstract

BASIC PENTACYSTEINE (BPC) transcription factors have been identified in a large variety of plant species. In Arabidopsis thaliana there are seven BPC genes, which, except for BPC5, are expressed ubiquitously. BPC genes are functionally redundant in a wide range of developmental processes. Recently, we reported that BPC1 binds to guanine and adenine (GA)-rich consensus sequences in the SEEDSTICK (STK) promoter in vitro and induces conformational changes. Here we show by chromatin immunoprecipitation experiments that in vivo BPCs also bind to the consensus boxes, and when these were mutated, expression from the STK promoter was derepressed, resulting in ectopic expression in the inflorescence. We also reveal that SHORT VEGETATIVE PHASE (SVP) is a direct regulator of STK. SVP is a floral meristem identity gene belonging to the MADS box gene family. The SVP-APETALA1 (AP1) dimer recruits the SEUSS (SEU)-LEUNIG (LUG) transcriptional cosuppressor to repress floral homeotic gene expression in the floral meristem. Interestingly, we found that GA consensus sequences in the STK promoter to which BPCs bind are essential for recruitment of the corepressor complex to this promoter. Our data suggest that we have identified a new regulatory mechanism controlling plant gene expression that is probably generally used, when considering BPCs' wide expression profile and the frequent presence of consensus binding sites in plant promoters.

Cucumber CsBPCs Regulate the Expression of CsABI3 during Seed Germination

“…In contrast to chromatin factors PcG and TrxG that are well-conserved between animals and plants, there are no homologs of the animal GAFs in plants (Strutt et al, 1997; Francis and Kingston, 2001; Lehmann, 2004; Muller and Kassis, 2006; Schuettengruber et al, 2009; Berger and Dubreucq, 2012). Given the functional similarities between BPCs and GAFs, BPCs were suggested to be GAF substitutes in plants (Berger et al, 2011; Berger and Dubreucq, 2012; Simonini et al, 2012). Nevertheless, a GAGA element in the LEC2 gene promoter bound by BPC1 was not required for the activity of PcG or TrxG, suggesting that BPCs might have other unknown functions (Berger et al, 2011).…”

The Arabidopsis GAGA-Binding Factor BASIC PENTACYSTEINE6 Recruits the POLYCOMB-REPRESSIVE COMPLEX1 Component LIKE HETEROCHROMATIN PROTEIN1 to GAGA DNA Motifs

“…Moreover, group I BBR/BPC members have the capacity to bend DNA, presumably through a molecular mechanism that involves multimerization of the proteins (Kooiker et al, 2005;Simonini et al, 2012). In addition, Arabidopsis BPC1 regulates MADS box gene expression and the recruitment of the SEUSS (SEU)-LEUNIG (LUG) transcriptional suppressor complex to repress the homeotic STK locus (Simonini et al, 2012). These findings on plant GAFs are reminiscent of the tight control of homeotic genes described for animal GAF families.…”

“…In addition, group I and group II BBR/BPC members might possibly compete for binding to GAGA motifs in similar and partially overlapping gene targets. Therefore, it might be possible that group I BBR/BPC proteins can partially complement the repressive group II function at some vacant GAGA loci in bpc4 bpc6 plants independently of PcG members via the SEU/LUG suppressor complex, which presumably acts through a different mechanism (Simonini et al, 2012;Lee et al, 2014).…”

“…The group I BBR/BPC protein BPC1 is essential for the activation of the TF genes LEAFY COTYLEDON2 (LEC2), INNER NO OUTER (INO), and SEEDSTICK (STK), which control ovule and embryo development (Meister et al, 2004;Kooiker et al, 2005;Berger et al, 2011). Moreover, group I BBR/BPC members have the capacity to bend DNA, presumably through a molecular mechanism that involves multimerization of the proteins (Kooiker et al, 2005;Simonini et al, 2012). In addition, Arabidopsis BPC1 regulates MADS box gene expression and the recruitment of the SEUSS (SEU)-LEUNIG (LUG) transcriptional suppressor complex to repress the homeotic STK locus (Simonini et al, 2012).…”

Molecular aspects of zygotic embryogenesis in sunflower (Helianthus annuus L.): correlation of positive histone marks with HaWUS expression and putative link HaWUS/HaL1L

“…BPCs are retained functionally equivalent (Berger and Dubreucq 2012;Simonini et al 2012) to GAGA-factors (GAFs) that are not yet recognized in plants on the basis of conserved amino acid sequences. In animals, e.g., Drosophila melanogaster, GAGA-factors can interact with GAGAG sequences to recruit TrxG and PcG (Berger and Dubreucq 2012).…”