The E2/E3 enzyme UBE2O ubiquitylates diverse clients to mediate important processes, including targeting unassembled `orphan' proteins for quality control and clearing ribosomes during erythropoiesis. How quality-control factors, such as UBE2O, select clients on the basis of heterogeneous features is largely unknown. Here, we show that UBE2O client selection is regulated by ubiquitin binding and a cofactor, NAP1L1. Attaching a single ubiquitin onto a client enhances UBE2O binding and multi-mono-ubiquitylation. UBE2O also repurposes the histone chaperone NAP1L1 as an adapter to recruit a subset of clients. Cryo-EM structures of human UBE2O in complex with NAP1L1 reveal a malleable client recruitment interface that is autoinhibited by the intrinsically reactive UBC domain. Adding a ubiquitylated client identifies a distinct ubiquitin-binding SH3-like domain required for client selection. Our findings reveal how multivalency and a feed-forward mechanism drive the selection of protein quality-control clients.
JoeLoparoOur first paper investigating the mechanism of the bacterial cell wall machinery. In this collaborative work with the Kruse and Bernhardt labs, we show how conformational dynamics of RodA-PBP2 coordinate its enzymatic activities. t.co/SnwZ8p4kF0