The ZmbZIP22 Transcription Factor Regulates 27-kD γ-Zein Gene Transcription during Maize Endosperm Development
The ZmbZIP22 Transcription Factor Regulates 27-kD γ-Zein Gene Transcription during Maize Endosperm Development
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ZmbZIP22 转录因子在玉米胚乳发育过程中调节 27-kD γ-玉米醇溶蛋白基因转录
DOI：
10.1105/tpc.18.00422
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发表时间：
2018-10-01
期刊：
影响因子：
11.6
通讯作者：
Song, Rentao
中科院分区：
文献类型：
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作者：
Li, Chaobin;Yue, Yihong;Song, Rentao
玉米醇溶蛋白是玉米籽粒中含量最丰富的贮藏蛋白质，因此会影响玉米的营养品质和质地。27-kD的伽马-玉米醇溶蛋白高度表达，在蛋白体的形成中起着至关重要的作用。一些转录因子(Tf)(O2、PBF1、OHP1和OHP2)调控27-kD的伽马-玉米醇溶蛋白基因的表达，但其转录调控的复杂性尚不完全清楚。在这里，通过探针亲和纯化和质谱分析，我们鉴定了ZmbZIP22，一个与27-kD的伽马-玉米醇溶蛋白启动子结合的转铁蛋白。ZmbZIP22是一种在胚乳中特异表达的bZIP型转铁蛋白。ZmbZIP22与27-KD中的ACAGCTCA盒直接结合。γ-Zein启动子并激活其在野生烟草细胞中的表达。在CRISPR/Cas9产生的zmbzip22突变体中，27-kD的伽马-玉米醇溶蛋白基因的表达显著降低。CHIP-SEQ(染色质免疫沉淀结合高通量测序)证实ZmbZIP22与27-kD结合。体内的伽马-玉米醇溶蛋白启动子，并确定了ZmbZIP22的其他直接靶点。ZmbZIP22能与PBF1、OHP1和OHP2相互作用，但不能与O2相互作用。使用这些转录因子的不同组合进行的转录激活分析显示，27-kD伽马-玉米醇溶蛋白启动子的转录活性有多种相互作用模式。因此，ZmbZIP22与其他已知的转录因子一起调节27-kD的伽马-玉米醇溶蛋白基因的表达。
Zeins are the most abundant storage proteins in maize (Zea mays) kernels, thereby affecting the nutritional quality and texture of this crop. 27-kD gamma-zein is highly expressed and plays a crucial role in protein body formation. Several transcription factors (TFs) (O2, PBF1, OHP1, and OHP2) regulate the expression of the 27-kD gamma-zein gene, but the complexity of its transcriptional regulation is not fully understood. Here, using probe affinity purification and mass spectrometry analysis, we identified ZmbZIP22, a TF that binds to the 27-kD gamma-zein promoter. ZmbZIP22 is a bZIP-type TF that is specifically expressed in endosperm. ZmbZIP22 bound directly to the ACAGCTCA box in the 27-kD. gamma-zein promoter and activated its expression in wild tobacco (Nicotiana benthamiana) cells. 27-kD gamma-zein gene expression was significantly reduced in CRISPR/Cas9-generated zmbzip22 mutants. ChIP-seq (chromatin immunoprecipitation coupled to high-throughput sequencing) confirmed that ZmbZIP22 binds to the 27-kD. gamma-zein promoter in vivo and identified additional direct targets of ZmbZIP22. ZmbZIP22 can interact with PBF1, OHP1, and OHP2, but not O2. Transactivation assays using various combinations of these TFs revealed multiple interaction modes for the transcriptional activity of the 27-kD gamma-zein promoter. Therefore, ZmbZIP22 regulates 27-kD gamma-zein gene expression together with other known TFs.