Rice SPX1 and SPX2 inhibit phosphate starvation responses through interacting with PHR2 in a phosphate-dependent manner
Rice SPX1 and SPX2 inhibit phosphate starvation responses through interacting with PHR2 in a phosphate-dependent manner
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DOI：
10.1073/pnas.1404680111
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发表时间：
2014-10-14
影响因子：
11.1
通讯作者：
Wu, Ping
中科院分区：
文献类型：
--
作者：
Wang, Zhiye;Ruan, Wenyuan;Wu, Ping
在植物中，感知外部和内部营养物质的水平对于重新编程转录组和适应波动的环境至关重要。磷酸盐（Pi）是植物的重要营养物质，拟南芥（AtPHR1）及其同源基因（如水稻（Oryza sativa）PHR2）控制着大量的Pi饥饿响应基因。AtPHR1和OsPHR2的表达对Pi饥饿的反应不是很大，这就提出了一个问题，即植物如何感知细胞Pi水平的变化以激活中央调节器。SPX [命名SYG1（酵母gpa1的抑制剂），PHO81（CDK抑制剂酵母PHO途径），和XPR1（异嗜性和多嗜性逆转录病毒受体）的蛋白质，只港口的SPX结构域的报道参与负调控的Pi饥饿反应。在这里，我们表明，核定位的SPX蛋白SPX1和SPX2是PI依赖的抑制剂的活性OsPHR2在水稻。事实上，SPX1和SPX2蛋白通过其SPX结构域与PHR2相互作用，抑制其与P1BS的结合（PHR1结合序列：GNATATNC）。体内数据以及使用纯化的SPX1、SPX2和OsPHR2蛋白的体外实验的结果表明，SPX1和SPX2对OsPHR2活性的抑制是Pi依赖性的。这些数据为SPX1和SPX2参与植物的Pi敏感机制提供了证据。
In plants, sensing the levels of external and internal nutrients is essential for reprogramming the transcriptome and adapting to the fluctuating environment. Phosphate (Pi) is a key plant nutrient, and a large proportion of Pi starvation-responsive genes are under the control of PHOSPHATE STARVATION RESPONSE REGULATOR 1 (PHR1) in Arabidopsis (AtPHR1) and its homologs, such as Oryza sativa (Os)PHR2 in rice. AtPHR1 and OsPHR2 expression is not very responsive to Pi starvation, raising the question as to how plants sense changes in cellular Pi levels to activate the central regulator. SPX [named after SYG1 (suppressor of yeast gpa1), Pho81 (CDK inhibitor in yeast PHO pathway), and XPR1 (xenotropic and polytropic retrovirus receptor)] proteins that harbor only the SPX domain are reported to be involved in the negative regulation of Pi starvation responses. Here, we show that the nuclear localized SPX proteins SPX1 and SPX2 are Pi-dependent inhibitors of the activity of OsPHR2 in rice. Indeed, SPX1 and SPX2 proteins interact with PHR2 through their SPX domain, inhibiting its binding to P1BS (the PHR1-binding sequence: GNATATNC). In vivo data, as well as results from in vitro experiments using purified SPX1, SPX2, and OsPHR2 proteins, showed that SPX1 and SPX2 inhibition of OsPHR2 activity is Pi-dependent. These data provide evidence to support the involvement of SPX1 and SPX2 in the Pi-sensing mechanism in plants.