Kadono Takashi, Miyagawa-Yamaguchi Arisa, Kira Nozomu, Tomaru Yuji, Okami Takuma, Yoshimatsu Takamichi, Hou Liyuan, Ohama Takeshi, Fukunaga Kazunari, Okauchi Masanori, Yamaguchi Haruo, Ohnishi Kohei, Falciatore Angela, Adachi Masao
Laboratory of Aquatic Environmental Science (LAQUES), Faculty of Agriculture, Kochi University, Otsu-200, Monobe, Nankoku, Kochi 783-8502, Japan.
The United Graduate School of Agricultural Sciences, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime, 790-8566 Japan.
Sci Rep. 2015 Dec 22;5:18708. doi: 10.1038/srep18708.
Viruses are considered key players in phytoplankton population control in oceans. However, mechanisms that control viral gene expression in prominent microalgae such as diatoms remain largely unknown. In this study, potential promoter regions isolated from several marine diatom-infecting viruses (DIVs) were linked to the egfp reporter gene and transformed into the Pennales diatom Phaeodactylum tricornutum. We analysed their activity in cells grown under different conditions. Compared to diatom endogenous promoters, novel DIV promoter (ClP1) mediated a significantly higher degree of reporter transcription and translation. Stable expression levels were observed in transformants grown under both light and dark conditions, and high levels of expression were reported in cells in the stationary phase compared to the exponential phase of growth. Conserved motifs in the sequence of DIV promoters were also found. These results allow the identification of novel regulatory regions that drive DIV gene expression and further examinations of the mechanisms that control virus-mediated bloom control in diatoms. Moreover, the identified ClP1 promoter can serve as a novel tool for metabolic engineering of diatoms. This is the first report describing a promoter of DIVs that may be of use in basic and applied diatom research.
病毒被认为是海洋中浮游植物种群控制的关键因素。然而，在诸如硅藻等重要微藻中控制病毒基因表达的机制仍 largely 未知。在本研究中，从几种感染海洋硅藻的病毒（DIVs）中分离出的潜在启动子区域与 egfp 报告基因相连，并转化到羽纹纲硅藻三角褐指藻中。我们分析了它们在不同条件下生长的细胞中的活性。与硅藻内源性启动子相比，新型 DIV 启动子（ClP1）介导的报告基因转录和翻译程度显著更高。在光照和黑暗条件下生长的转化体中均观察到稳定的表达水平，并且与生长指数期相比，在静止期细胞中报告了高水平的表达。在 DIV 启动子序列中也发现了保守基序。这些结果有助于鉴定驱动 DIV 基因表达的新型调控区域，并进一步研究控制硅藻中病毒介导的藻华控制的机制。此外，鉴定出的 ClP1 启动子可作为硅藻代谢工程的新型工具。这是第一份描述可能用于基础和应用硅藻研究的 DIVs 启动子的报告。
