Site-specific modification of the 6-amino group of adenosine in RNA by an interstrand functionality-transfer reaction with an s-functionalized 4-thiothymidine

Non-natural RNA modifications have been widely used to study the function and structure of RNA. Expanding the study of RNA further requires versatile and efficient tools for site-specific RNA modification. We recently established a new strategy for the site-specific modification of RNA based on a functionality-transfer reaction between an oligodeoxynucleotide (ODN) probe and an RNA substrate. 2′-Deoxy-6-thioguanosine was used to anchor the transfer group, and the 4-amino group of cytosine or the 2-amino group of guanine was specifically modified. In this study, 2′-deoxy-4-thiothymidine was adopted as a new platform to target the 6-amino group of adenosine. The (E)-pyridinyl vinyl keto transfer group was attached to the 4-thioT in the ODN probe, and it was efficiently and specifically transferred to the 6-amino group of the opposing adenosine in RNA in the presence of CuCl₂. This method expands the available RNA target sites for specific modification. Requesting a transfer: In our strategy for the site-specific modification of RNA, 2′-deoxy-4-thiothymidine (4-thioT) was adopted as a new platform. In the presence of CuCl₂, The (E)-pyridinyl vinyl-keto transfer group attached to the 4-thioT in an ODN was efficiently and specifically transferred to the 6-amino group of the opposing adenosine in RNA.