经典RNA ligase

Classic RNA and DNA ligases share a core adenylyltransferase domain and an active site composed of conserved amino acid sequence motifs. Classic RNA ligases can be divided into two main classes: the Rnl1 family and the Rnl2 family. Rnl2 ligases, like DNA ligases, prefer to seal 3′-OH/5′-PO₄ nicks in double-stranded substrates. By contrast, Rnl1 ligases prefer to join single-stranded ends, especially within stem-loop structures. The reported substrate preference for RtcB is similar to that of Rnl1. However, the crystal structures of RtcB revealed a novel fold and active site (12–14), reflecting the uniqueness of RtcB in terms of its biochemical mechanism.

Cross-over of RNA 3′-phosphate ligase into the DNA world | PNAS

经典的RNA和DNA连接酶共享一个核心腺苷基转移酶结构域和一个由保守的氨基酸序列基序组成的活性位点。经典的RNA连接酶可分为两大类：Rnl1家族和Rnl2家族。Rnl2连接酶与DNA连接酶一样，更倾向于封闭双链底物中的3 ‘ -OH/5 ‘ -PO ₄ 缺口。相比之下，Rnl1连接酶更倾向于连接单链末端，特别是在茎环结构中。RtcB对底物的偏好与Rnl1相似。然而，RtcB的晶体结构显示出新的褶皱和活性位点（12-14），反映了RtcB在生化机制上的独特性。