RNase J enzymes are metallohydrolases that are involved in RNA maturation and RNA recycling, govern gene expression in bacteria, and catalyze both exonuclease and endonuclease activity. The catalytic activity of RNase J is regulated by multiple mechanisms which include oligomerization, conformational changes to aid substrate recognition, and the metal cofactor at the active site. However, little is known of how RNase J paralogs differ in expression and activity. Here we describe structural and biochemical features of two Staphylococcus epidermidis RNase J paralogs, RNase J1 and RNase J2. RNase J1 is a homodimer with exonuclease activity aided by two metal cofactors at the active site. RNase J2, on the other hand, has endonuclease activity and one metal ion at the active site and is predominantly a monomer. We note that the expression levels of these enzymes vary across Staphylococcal strains. Together, these observations suggest that multiple interacting RNase J paralogs could provide a strategy for functional improvisation utilizing differences in intracellular concentration, quaternary structure, and distinct active site architecture despite overall structural similarity.

中文翻译：

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两种表皮葡萄球菌 RNase J 旁系同源物 RNase J1 和 RNase J2 的结构和生化特征

RNase J 酶是金属水解酶，参与 RNA 成熟和 RNA 回收，控制细菌中的基因表达，并催化核酸外切酶和核酸内切酶活性。RNase J 的催化活性受到多种机制的调节，包括寡聚、帮助底物识别的构象变化以及活性位点的金属辅因子。然而，人们对 RNase J 旁系同源物在表达和活性方面有何不同知之甚少。在这里，我们描述了两种表皮葡萄球菌 RNase J 旁系同源物 RNase J1 和 RNase J2 的结构和生化特征。RNase J1 是一种同型二聚体，具有核酸外切酶活性，由活性位点的两个金属辅因子辅助。另一方面，RNase J2 具有核酸内切酶活性，在活性位点有一个金属离子，并且主要是单体。我们注意到这些酶的表达水平因葡萄球菌菌株而异。总之，这些观察结果表明，尽管总体结构相似，但多个相互作用的 RNase J 旁系同源物可以利用细胞内浓度、四级结构和不同活性位点结构的差异提供功能即兴发挥的策略。