两项特殊末端RNA鉴定工作

第一个是2015年用Ecoli RTCB在yeast中体外筛选5′-OH末端RNA.

Global analysis of RNA cleavage by 5′-hydroxyl RNA sequencing | Nucleic Acids Research | Oxford Academic

第二个是2019年在mouse issue筛选2’3-cP末端RNA.

Genome-wide identification of short 2′,3′-cyclic phosphate-containing RNAs and their regulation in aging | PLOS Genetics

讨论部分比较有趣：

In this study, we unraveled a previously hidden layer of transcriptome by comprehensively identifying short cP-RNA species expressed in mouse tissues. Each cP-RNA library, obtained by cP-RNA-seq, commonly comprised previously uninterrogated cP-RNA species that are expected to be generated by specific RNA cleavage between cytidine and adenosine (S11 Fig). The endoribonuclease generating the identified cP-RNAs is unknown but should possess highly specific recognition and cleavage activity for the 5′-CA-3′ sequence. ANG might be the candidate enzyme because ANG produces cP-RNAs [10,28] and shows the highest activity toward the 5′-CA-3′ among four examined dinucleotides in a previous study [29]. Among other cP-generating ribonucleases, GCN4 shows high cleavage activity between C and A [30]. Because cP-RNAs are not evenly produced from overall sequences of substrate RNAs but rather derived from specific sites, the RNA cleavage activity to generate cP-RNAs might be exquisitely regulated. Further investigations are required to clarify the enzyme and its activity for the generation of the cP-RNAs identified in this study. Considering the already-proven functional significance of tRNA-derived cP-RNAs [6,7,8,9,10], it is not surprising that the identified cP-RNAs themselves have functional significance. Their abundance and expression from only specific sites of substrate RNAs might also imply their expression as functional molecules. The reduction of cP-RNA generation through aging implied its physiological relevance. It will be intriguing to examine further the cellular factors that influence, or are influenced by, the expression of cP-RNAs and their underlying molecular mechanisms, which will define cP-RNAs as an abundant class of functional non-coding RNAs.

可以学习的点是其中两个candidate endoribonuclease: ANG, GCN4.

以及提供了RTCB作为RNA ligase的选择性来源之一可能是某种核糖核酸内切酶的底物特异性：Because cP-RNAs are not evenly produced from overall sequences of substrate RNAs but rather derived from specific sites, the RNA cleavage activity to generate cP-RNAs might be exquisitely regulated.

以及这方面的后续研究意义，可能提供一种全新的有功能的non-coding RNA—cP-RNAs.