Structural insights into ADP-ribosylation of ubiquitin by Deltex family E3 ubiquitin ligases.
Chatrin, C., Gabrielsen, M., Buetow, L., Nakasone, M.A., Ahmed, S.F., Sumpton, D., Sibbet, G.J., Smith, B.O., Huang, D.T.(2020) Sci Adv 6
- PubMed: 32948590 
- DOI: https://doi.org/10.1126/sciadv.abc0418
- Primary Citation of Related Structures:  
6Y5N, 6Y5P - PubMed Abstract: 
Cellular cross-talk between ubiquitination and other posttranslational modifications contributes to the regulation of numerous processes. One example is ADP-ribosylation of the carboxyl terminus of ubiquitin by the E3 DTX3L/ADP-ribosyltransferase PARP9 heterodimer, but the mechanism remains elusive. Here, we show that independently of PARP9, the conserved carboxyl-terminal RING and DTC (Deltex carboxyl-terminal) domains of DTX3L and other human Deltex proteins (DTX1 to DTX4) catalyze ADP-ribosylation of ubiquitin's Gly 76 Structural studies reveal a hitherto unknown function of the DTC domain in binding NAD + Deltex RING domain recruits E2 thioesterified with ubiquitin and juxtaposes it with NAD + bound to the DTC domain to facilitate ADP-ribosylation of ubiquitin. This ubiquitin modification prevents its activation but is reversed by the linkage nonspecific deubiquitinases. Our study provides mechanistic insights into ADP-ribosylation of ubiquitin by Deltex E3s and will enable future studies directed at understanding the increasingly complex network of ubiquitin cross-talk.
Organizational Affiliation: 
Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK.