第二信使c-di-GMP参与调节细菌多种重要生理功能，但关于c-di-GMP调控机制的报道不多。已有的研究表明c-di-GMP参与调控蓝细菌细胞的运动力、细胞聚集和异形胞分化，但是调控的分子机制尚不清楚。本项目将围绕c-di-GMP调控Anabaena sp. PCC7120异形胞发育的分子机制展开研究。首先通过构建超表达菌株及导入基于FRET的c-di-GMP生物传感器确定c-di-GMP水平与异形胞分化的关系；其次通过Pull-Down、质谱、ITC和缺失突变体表型分析等手段，筛选与异形胞发育有关的c-di-GMP受体；最后通过转录组学和蛋白组学分析找到c-di-GMP信号通路中受c-di-GMP受体调控的靶蛋白，并运用ITC、EMSA、蛋白交联等技术研究调控的分子机制。该研究成果将加深对蓝细菌异形胞分化发育调控模式的认识，扩展c-di-GMP调控细菌生理功能的范围。

c-di-GMP as a second messenger regulates a variety of important physiological functions in bacteria, which enable them to adapt quickly to the environmental changes. But, till now, the molecular regulatory mechanisms of c-di-GMP remain poorly understood. Although c-di-GMP has been reported to control cell motility, cell aggregation and heterocyst differentiation in cyanobacteria, the specific molecular mechanisms are still not clear. In this project, we will focus on the studies of molecular mechanism of heterocyst development regulated by c-di-GMP in the cyanobacteria Anabaena sp. PCC7120. To achieve this, specific relationship between intracellular c-di-GMP level and heterocyst differentiation was firstly established by analyzing the phenotype of strains which make either a higher, or lower, than normal levels of c-di-GMP, combined with the introduction of a c-di-GMP biosensor which based on fluorescence resonance energy transfer. Secondly, Pull-Down assay, Mass spectrometry technology, ITC analysis and phenotype analysis of the deletion mutant strains will be used to screen c-di-GMP receptor related to heterocyst development. Finally, the regulator targets of c-di-GMP receptors in the signaling pathways will be identified by transcriptomics and proteomics analysis, and the relationship between c-di-GMP, c-di-GMP receptors and their targets will be defined by ITC, EMSA and protein cross-linking and other technological means. Based on these findings, we will elucidate the molecular mechanisms on c-di-GMP signaling in heterocyst development, which will deepen the understanding of the regulatory model of heterocyst differentiation in cyanobacteria, and expand the scope of c-di-GMP regulation on bacterial physiology.