Ubiquitylation of nucleic acids by DELTEX ubiquitin E3 ligase DTX3L.

The recent discovery of non-proteinaceous ubiquitylation substrates broadened our understanding of this modification beyond conventional protein targets. However, the existence of additional types of substrates remains elusive. Here, we present evidence that nucleic acids can also be directly ubiquitylated via ester bond formation. DTX3L, a member of the DELTEX family E3 ubiquitin ligases, ubiquitylates DNA and RNA in vitro and that this activity is shared with DTX3, but not with the other DELTEX family members DTX1, DTX2 and DTX4. DTX3L shows preference for the 3′-terminal adenosine over other nucleotides. In addition, we demonstrate that ubiquitylation of nucleic acids is reversible by DUBs such as USP2, JOSD1 and SARS-CoV-2 PLpro. Overall, our study proposes reversible ubiquitylation of nucleic acids in vitro and discusses its potential functional implications. Synopsis: Nucleic acids are a novel type of ubiquitylation substrate. Nucleic acids are ubiquitylated by DELTEX ubiquitin E3 ligase DTX3L, targeting the 3′-terminal adenosine nucleotides at their 3′ hydroxyl groups. KH domain-containing DELTEX E3 ligase DTX3 and DTX3L possess nucleic acids ubiquitylation activity while WWE domain-containing DELTEX E3 ligase DTX1, DTX2 as well as DTX4 do not. Ubiquitylation of nucleic acids by DTX3L could block cleavage by 3′–5′ nuclease and represents a reversible process. Nucleic acids are a novel type of ubiquitylation substrate. [ABSTRACT FROM AUTHOR]