Sulfide-quinone oxidoreductase (SQR) is a key enzyme of sulfide metabolism in metazoans, and responsible for oxidizing sulfide into thiosulfate and transmitting the generated electrons to the ubiquinone. It has been revealed that the sqr mRNA level increases significantly in echiuran worm Urechis unicinctus exposed to sulfide, and HSF1, NF1 and Sp1 have been verified to participate in its transcriptional regulation. In this study, we obtained 23 potential transcription factors interacting possibly with the proximal region (−391 to +50) of sqr promoter, and focused on the RWD domain-containing 1 (Rwdd1), a protein with the maximum number of clones in yeast one-hybrid (Y1H) screening, to investigate its transcriptional regulation to U. unincitus sqr. The ChIP and EMSA assays identified that the Rwdd1 can bind directly to the promoter (+18/+36) of U. unicinctus sqr. The point mutation and transient transfection experiments discovered that TACG was the key sequence of the DNA element bound by the Rwdd1. Furthermore, the U. unicinctus Rwdd1 (UuRwdd1) was identified to be a transcription repressor inhibiting the sqr promoter activity, and the SUMOylation of UuRwdd1 at the lysine of 90^th enhanced its inhibitory effect on sqr transcription further. Western blotting found Rwdd1 responded to sulfide in hindguts from U. unincitus, and the protein content showed a remarkable drop in hindgut nuclei in the early sulfide exposure, and then increased significantly both in the total protein and the nuclear protein extract. We suggested that the Rwdd1 is a novel transcription factor, and these data improve our understanding of the sqr transcriptional regulation and the mitochondrial sulfide metabolism.

硫化物醌氧化还原酶（SQR）是后生动物中硫化物代谢的关键酶，负责将硫化物氧化为硫代硫酸盐并将生成的电子传输至泛醌。已经发现在暴露于硫化物的棘鱼蠕虫Urechis unicinctus中，sqr mRNA水平显着增加，并且已证实HSF1，NF1和Sp1参与了其转录调控。在这项研究中，我们获得了23个可能与sqr启动子的近端区域（-391至+50）相互作用的潜在转录因子，并重点研究了含有RWD结构域的1（Rwdd1），该蛋白质在酵母中具有最大的克隆数目。一杂种（Y1H）筛选，以研究其转录调控U.unincitus sqr。ChIP和EMSA分析确定Rwdd1可以直接结合到U. unicinctus sqr的启动子（+ 18 / + 36）。点突变和瞬时转染实验发现，TACG是与Rwdd1结合的DNA元件的关键序列。此外，U. unicinctus Rwdd1（支原体Rwdd1）被鉴定为一种转录阻遏抑制SQR启动子活性，和的SUMO化的Uu Rwdd1以90赖氨酸^个增强其抑制效果SQR进一步转录。Western印迹发现Rwdd1对U.unitusitus后肠中的硫化物有反应，并且在早期硫化物暴露下，后肠核中的蛋白质含量显着下降，然后在总蛋白和核蛋白提取物中均显着增加。我们建议Rwdd1是一种新型的转录因子，这些数据提高了我们对sqr转录调控和线粒体硫化物代谢的了解。