Molecular Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10065, USA.
Proc Natl Acad Sci U S A. 2012 Feb 14;109(7):2296-301. doi: 10.1073/pnas.1116827109. Epub 2012 Jan 27.
Pnkp is the end-healing and end-sealing component of an RNA repair system present in diverse bacteria from ten different phyla. To gain insight to the mechanism and evolution of this repair system, we determined the crystal structures of the ligase domain of Clostridium thermocellum Pnkp in three functional states along the reaction pathway: apoenzyme, ligase • ATP substrate complex, and covalent ligase-AMP intermediate. The tertiary structure is composed of a classical ligase nucleotidyltransferase module that is embellished by a unique α-helical insert module and a unique C-terminal α-helical module. Structure-guided mutational analysis identified active site residues essential for ligase adenylylation. Pnkp defines a new RNA ligase family with signature structural and functional properties.
Pnkp 是一种存在于十个不同门的多种细菌中的 RNA 修复系统的末端修复和末端密封组件。为了深入了解该修复系统的机制和进化,我们沿着反应途径确定了 Clostridium thermocellum Pnkp 的连接酶结构域在三种功能状态下的晶体结构:无酶、连接酶 • ATP 底物复合物和共价连接酶-AMP 中间产物。三级结构由一个经典的连接酶核苷酸转移酶模块组成,该模块被一个独特的α-螺旋插入模块和一个独特的 C 末端α-螺旋模块修饰。结构导向的突变分析确定了连接酶腺苷酰化所必需的活性位点残基。Pnkp 定义了一个具有特征结构和功能特性的新 RNA 连接酶家族。