Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Chongqing Medical University, Chongqing 400016, People's Republic of China.
Protein J. 2010 Nov;29(8):583-90. doi: 10.1007/s10930-010-9293-x.
RNase E functions as the rate-limiting enzyme in the global mRNA metabolism as well as in the maturation of functional RNAs. The endoribonuclease, binding to the PNPase trimer, the RhlB monomer, and the enolase dimer, assembles into an RNA degradosome necessary for effective RNA metabolism. The RNase E processing is found to be negatively regulated by the protein modulator RraA which appears to work by interacting with the non-catalytic region of the endoribonuclease and significantly reduce the interaction between RNase E and PNPase, RhlB and enolase of the RNA degradosome. Here we report the crystal structure of RraA from P. aeruginosa to a resolution of 2.0 Å. The overall architecture of RraA is very similar to other known RraAs, which are highly structurally conserved. Gel filtration and dynamic light scattering experiments suggest that the protein regulator is arranged as a hexamer, consistent with the crystal packing of "a dimer of trimer" arrangement. Structure and sequence conservation analysis suggests that the hexamer RraA contains six putative charged protein-protein interaction sites which may serve as binding sites for RNase E.
RNase E 作为全局 mRNA 代谢以及功能性 RNA 成熟的限速酶发挥作用。内切核酸酶与 PNPase 三聚体、RhlB 单体和烯醇酶二聚体结合，组装成 RNA 降解体，这对于有效的 RNA 代谢是必需的。发现 RNase E 的加工受到蛋白调节剂 RraA 的负调控，该调节剂似乎通过与内切核酸酶的非催化区域相互作用起作用，并显著降低 RNase E 与 PNPase、RhlB 和 RNA 降解体中的烯醇酶之间的相互作用。在此，我们报道了来自铜绿假单胞菌的 RraA 的晶体结构，分辨率为 2.0 Å。RraA 的整体结构与其他已知的 RraA 非常相似，高度结构保守。凝胶过滤和动态光散射实验表明，该蛋白调节剂排列为六聚体，与“三聚体二聚体”排列的晶体包装一致。结构和序列保守性分析表明，六聚体 RraA 包含六个假定的带电荷的蛋白-蛋白相互作用位点，这些位点可能作为 RNase E 的结合位点。
