蓝细菌Anabaena PCC 7120中RNA酶复合体RNase E-PNPase-RNase II调控胞内RNA代谢的机制

RNA降解体是细菌中发现的以RNA酶及相关蛋白为主要组分、对胞内RNA代谢有重要影响的蛋白复合体。尽管在E. coli等少数模式菌株中RNA降解体的组分及详细组装机制已被解析，但其生物学功能仍远未被阐明。我们发现蓝细菌Anabaena中内切核糖核酸酶RNase E能与PNPase、RNase II这两种外切核糖核酸酶形成RNA酶复合体。该复合体组成及组装方式与其他已知RNA降解体显著不同，代表了一种新型RNA降解体。本项目拟运用生化、遗传学、组学等手段进一步解析该RNA酶复合体的详细组装机制、酶学特性及胞内功能。将重点对复合体各组分条件突变体、互作突变体及野生型菌株在不同条件下的转录组和生理活性进行比较，以揭示Anabaena中RNase E、PNPase、RNase II相互协作调控RNA代谢的机理。预期结果将进一步加深人们对细菌中RNA降解体生物学功能和RNA代谢调控多样性的认识。

RNA degradosome, a protein complex whose principal components include ribonucleases and other proteins involved in RNA degradation, is found in many bacteria. It is generally believed that degradosome, via highly cooperative activities of its components, guarantees efficient metabolism of cellular RNAs. In E. coli and a few other model bacteria, the composition and assembly mechanism have been well characterized; however, the biological roles of degradosome is still far from being illustrated. We recently found that in the cyanobacterium Anabaena PCC 7120, the endoribonuclease RNase E could associate with two exoribonucleases, PNPase and RNase II, to form a ribonuclease complex resembling the E. coli RNA degradosome. It however differs significantly from the known RNA degradosomes from other bacteria, in both composition and assembling, thus representing a novo type of RNA degradosome. In this project, we aim to reveal the biological functions of the RNase E-PNPase-RNase II complex by investing its assembly mechanism, catalytic properties and in vivo functions, using combined approaches of biochemistry, transcriptomics, genetics, and others. Particularly, we will grow the wildtype strain, the conditional mutants of RNase E, RNase II and PNPase, and the mutants of their assembly under different conditions, then compare their transcriptomes and physiological activities. By doing so, we will be able to reveal how RNase E, PNPase and RNase II cooperatively regulate cellular RNA metabolism in Anabaena. The expected results of this project would advance our understanding of the biological functions of RNA degradosome, as well as the diversity of RNA metabolism regulation in bacteria.