Deciphering the Molecular Mechanisms Underpinning the Transcriptional Control of Gene Expression by Master Transcriptional Regulators in Arabidopsis Seed. Issue 2 (12th April 2016)

• Record Type: Journal Article
• Authors: Baud, Sébastien; Kelemen, Zsolt; Thévenin, Johanne; Boulard, Céline; Blanchet, Sandrine; To, Alexandra; Payre, Manon; Berger, Nathalie; Effroy-Cuzzi, Delphine; Franco-Zorrilla, Jose Manuel; Godoy, Marta; Solano, Roberto; Thevenon, Emmanuel; Parcy, François; Lepiniec, Loïc; Dubreucq, Bertrand
• Is Part Of: Plant physiology. Volume 171:Issue 2(2016)
• Page Start: 1099
• Page End: 1112
• Publication Date: 2016-04-12
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1104/pp.16.00034
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract : LEC2, ABI3, and LEC1 synergistically interact to activate an oleosin promoter. Abstract: In Arabidopsis ( Arabidopsis thaliana ), transcriptional control of seed maturation involves three related regulators with a B3 domain, namely LEAFY COTYLEDON2 (LEC2), ABSCISIC ACID INSENSITIVE3 (ABI3), and FUSCA3 (ABI3/FUS3/LEC2 [AFLs]). Although genetic analyses have demonstrated partially overlapping functions of these regulators, the underlying molecular mechanisms remained elusive. The results presented here confirmed that the three proteins bind RY DNA elements (with a 5′-CATG-3′ core sequence) but with different specificities for flanking nucleotides. In planta as in the moss Physcomitrella patens protoplasts, the presence of RY-like (RYL) elements is necessary but not sufficient for the regulation of the OLEOSIN1 ( OLE1 ) promoter by the B3 AFLs. G box-like domains, located in the vicinity of the RYL elements, also are required for proper activation of the promoter, suggesting that several proteins are involved. Consistent with this idea, LEC2 and ABI3 showed synergistic effects on the activation of the OLE1 promoter. What is more, LEC1 (a homolog of the NF-YB subunit of the CCAAT-binding complex) further enhanced the activation of this target promoter in the presence of LEC2 and ABI3. Finally, recombinant LEC1 and LEC2 proteins produced in Arabidopsis protoplasts could form a ternary complex with NF-YC2 in vitro, providing a molecular explanation for their functional interactions. Taken together, these results allow us to propose a molecular model for the transcriptional regulation of seed genes by the L-AFL proteins, based on the formation of regulatory multiprotein complexes between NF-YBs, which carry a specific aspartate-55 residue, and B3 transcription factors.