State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresouces, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
Int J Mol Sci. 2020 Dec 11;21(24):9437. doi: 10.3390/ijms21249437.
The auxin response factor () transcription factors are a key component in auxin signaling and play diverse functions in plant growth, development, and stress response. s are regulated at the transcript level and posttranslationally by protein modifications. However, relatively little is known regarding the control of protein levels. We expressed five different s with an HA (hemagglutinin) tag and observed that their protein levels under the same promoter varied considerably. Interestingly, their protein levels were affected by several hormonal and environmental conditions, but not by the auxin treatment. ABA (abscisic acid) as well as 4 °C and salt treatments decreased the levels of , , and , but not that of , while 37 °C treatment increased the levels of the four s, suggesting that the protein levels are regulated by multiple factors. Furthermore, MG132 inhibited the reduction of level by ABA and 4 °C treatments, suggesting that these treatments decrease level through 26S proteasome-mediated protein degradation. It was also found that ABA treatment drastically increased ubiquitination, without strongly affecting the ubiquitination profile of the total proteins. Together, these results reveal another layer of control on s, which could serve to integrate multiple hormonal and environmental signals into the -regulated gene expression.
生长素响应因子（ARF）转录因子是生长素信号转导的关键组成部分，在植物生长、发育和应激反应中发挥多种功能。ARFs 在转录水平和翻译后通过蛋白质修饰进行调节。然而，关于 ARF 蛋白水平的控制，我们知之甚少。我们表达了带有 HA（血凝素）标签的五个不同的 ARF，并观察到它们在相同启动子下的蛋白水平差异很大。有趣的是，它们的蛋白水平受到多种激素和环境条件的影响，但不受生长素处理的影响。ABA（脱落酸）以及 4°C 和盐处理降低了 ARF、ARF、ARF 和 ARF 的水平，但不影响 ARF 的水平，而 37°C 处理增加了这四个 ARF 的水平，表明 ARF 蛋白水平受多种因素调节。此外，MG132 抑制 ABA 和 4°C 处理降低 ARF 水平，表明这些处理通过 26S 蛋白酶体介导的蛋白质降解降低 ARF 水平。还发现 ABA 处理大大增加了 ARF 的泛素化，而对总蛋白的泛素化谱没有强烈影响。总之，这些结果揭示了 ARF 水平的另一个调控层次，这可能有助于将多种激素和环境信号整合到 ARF 调节的基因表达中。
