Development of Ubiquitin‐Based Probe for Metalloprotease Deubiquitinases

Deubiquitinases (DUBs) are a family of enzymes that regulate the ubiquitin signaling cascade by removing ubiquitin from specific proteins in response to distinct signals. DUBs that belong to the metalloprotease family (metalloDUBs) contain Zn²⁺ in their active sites and are an integral part of distinct cellular protein complexes. Little is known about these enzymes because of the lack of specific probes. Described here is a Ub‐based probe that contains a ubiquitin moiety modified at its C‐terminus with a Zn²⁺ chelating group based on 8‐mercaptoquinoline, and a modification at the N‐terminus with either a fluorescent tag or a pull‐down tag. The probe is validated using Rpn11, a metalloDUB found in the 26S proteasome complex. This probe binds to metalloDUBs and efficiently pulled down overexpressed metalloDUBs from a HeLa cell lysate. Such probes may be used to study the mechanism of metalloDUBs in detail and allow better understanding of their biochemical processes.