宿主以细胞质中的解旋酶为基础识别检测病原体信号的发现，不仅具有重大的天然免疫基础生物学研究意义，更有不可估量的医学实用价值。尽管RIG-I家族解旋酶利用其解旋酶的dsRNA结合位点识别RNA并引起构型变化，结合线粒体上MAVS蛋白诱导干扰素产生的分子机理已初步阐明，但近年发现的DExH家族解旋酶识别病原体核酸及传导免疫信号的研究仍处在极为前期的阶段。本研究计划充分利用我们长期积累的解旋酶研究领域中的方法和经验，以DHX36/DHX9为研究主体，综合运用结构生物学、细胞生物学、分子生物学、生化和生物物理等多学科手段，纯化分离各个解旋酶组份蛋白，并通过生物大分子体外重构，组建以DHX36为主的4种免疫识别复合体，深入研究不同于RIG-I家族的DExH/RHA家族解旋酶在细胞质内特有的通路感受识别的分子机理。理解解旋酶在正常细胞内行使解旋酶功能和在感染细胞内作为病原体检测器的双重功能及转换机制。

In natural immunity studies, the discovery that hosts recognize and identify pathogen signals based on the helicase structure in cytoplasm has not only tremendous biological significance, but also inestimable medical values. RIG-I family helicases utilize their dsRNA binding sites to recognize RNA, which in turn leads to conformational changes, then bind to mitochondrial MAVS proteins, and finally induces the production of interferon. Although the molecular mechanism behind above phenomenon has been clarified preliminarily, the research about how DExH family helicase discovered in recent years to identify pathogen nucleic acid and conduct immune signal is still in the very early stage. This project plans to set DHX36/DHX9 as research objects, take advantage of our research methods and experience on helicases over 20 years, purify each helicase components, and construct four large immune recognition complexes with DHX36 through biological macromolecule in vitro reconstruction system. The goal of this project is to reveal the pathway recognition mechanism of DExH/RHA family helicases in cytoplasm which is different from RIG-I family, by the means of structural biology (X-ray diffraction and cryo-electron microscopy), cell biology, molecular biology, biochemistry, biophysics and other multidisciplinary methods. The implementation of this project will provide deep understanding about the dual functions of helicases including unwinding nucleic acids in normal cells and detecting pathogens in infected cells, and their conversion mechanism.