Cupriavidus pinatubonensis JMP134中H2S氧化代谢途径的调控机理研究

硫化氢（H2S）是重要的环境污染物，对细胞具有毒性和信号调控双重作用。它在生物体内的研究集中在自养菌，而缺乏异养菌硫氧化途径及调控过程研究。芳香化合物降解模式菌Cupriavidus pinatubonensis JMP134除具有我们新发现的硫醌氧化还原酶(SQR)-过硫化物双加氧酶(PDO)体系外，还具有自养菌氧化硫的Sox系统，亚硫酸盐氧化系统及同化硫酸盐还原系统。这些系统可能协同作用，因为有代谢中间物重叠。因此，H2S在异养菌体内的代谢与调控过程是一个综合的过程，需要多个调控蛋白协同作用。本研究以异养菌C. pinatubonensis JMP134为对象，通过分析各途径调控蛋白结合位点，构建启动子报告系统，通过敲除菌和野生菌的报告系统、代谢物分析确定各调控蛋白在H2S代谢中的作用，通过改变中间产物来分析对下游代谢调控过程的影响，获得综合调控途径，为利用异养菌进行硫污染治理奠定基础

Hydrogen sulfide (H2S) is an important environmental pollutant. It is toxic at high levels and essential as a signal molecule at low concentrations inside the cells. Little is known about its oxidation and regulation by heterotrophic bacteria. We have characterized a new H2S oxidation pathway involving sulfide:quinone oxidoreductase (SQR) and persulfide dioxygenase (PDO) in heterotrophic bacteria. Further, we have found that its metabolic intermediates and products of the new pathway can act as substrates for the Sox pathway and the assimilatory sulfate reduction pathway, making sulfur metabolism and regulation complex in heterotrophic bacteria. The proposed research will focus on Cupriavidus pinatubonensis JMP134, a well-characterized bacterium for the degradation of aromatic compounds. The bacterium contains the SQR-PDO system, the Sox system, and the assimilatory sulfur reduction system. The specific aims are to identify the regulators and analyze their binding sites to genes coding for each pathway, construct promoter reporting system to analyze the regulation function of the regulators using wild and regulator knock out strains. In addition, we can change the concentration of SQR-PDO intermediates by gene inactivation or overexpression; therefore, the sulfur metabolism and regulation governing the interactive pathways will be elucidated. The studies will help to establish the application of heterotrophic bacteria in sulfur bioremediation.