ZmMADS47 Regulates Zein Gene Transcription through Interaction with Opaque2.

Qing Yang,Rentao Song,Nathan M Springer,Weiwei Qi,Shanshan Wang,Qian Wang,Zhenyi Qiao,Ya’Nan Feng,Yuanping Tang,Nan Zhang

doi:10.1371/journal.pgen.1005991

Abstract

Zeins, the predominent storage proteins in maize endosperm, are encoded by multiple genes and gene families. However, only a few transcriptional factors for zein gene regulation have been functionally characterized. In this study, a MADS-box protein, namely ZmMADS47, was identified as an Opaque2 (O2) interacting protein via yeast two-hybrid screening. The N-terminal portion of ZmMADS47 contains a nuclear localization signal (NLS), and its C-terminal portion contains a transcriptional activation domain (AD). Interestingly, the transcriptional activation activity is blocked in its full length form, suggesting conformational regulation of the AD. Molecular and RNA-seq analyses of ZmMADS47 RNAi lines revealed down regulation of α-zein and 50-kD γ-zein genes. ZmMADS47 binds the CATGT motif in promoters of these zein genes, but ZmMADS47 alone is not able to transactivate the promoters. However, when both O2 and ZmMADS47 are present, the transactivation of these promoters was greatly enhanced. This enhancement was dependent on the AD function of ZmMADS47 and the interaction between ZmMADS47 and O2, but it was independent from the AD function of O2. Therefore, it appears interaction with O2 activates ZmMADS47 on zein gene promoters.

Highlights

In maize (Zea mays) kernels, starch, storage proteins and oil are the three main metabolic storage materials
Among them was a MADS-box protein showing high homology to OsMADS47 at 83% similarity; we named it ZmMADS47
To confirm interaction with O2, the full-length open reading frame (ORF) of ZmMADS47 was cloned into the pGADT7-Rec vector and transformed into yeast strain AH109 with pGBKT7-O2-2

Summary

Introduction

In maize (Zea mays) kernels, starch, storage proteins and oil are the three main metabolic storage materials. Zeins are the most abundant storage proteins and are encoded by different. ZmMADS47 Regulates Zein Expression classes of genes. Zeins are identified as α-, β-, γ- and δtypes based on difference in aqueous solubility and ability to form disulfide bands [1]. Α-zeins are divided into two major classes: 19-kD α-zeins (z1A, z1B, z1D), and 22-kD α-zeins (z1C) [2]. The other three zeins, including 16-kD, 27-kD and 50-kD proteins, all belong to γzein gene sub-family [4]. Due to their high levels of expression and complexity, zein gene transcriptional regulation has attracted the interest of researchers and breeders for decades

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Results

Conclusion