Here, we describe a stress-related protein, YdiU, and characterize YdiU as an enzyme that catalyzes the covalent attachment of uridine-5¡ä-monophosphate to a protein tyrosine/histidine residue, an unusual modification defined as UMPylation. Mn2+ serves as an essential co-factor for YdiU-mediated UMPylation. UTP and Mn2+ binding converts YdiU to an aggregate-prone state facilitating the recruitment of chaperones. The UMPylation of chaperones prevents them from binding co-factors or clients, thereby impairing their function.

Reference
Pubmed: Yang Y, Yue Y, Song N, Li C, Yuan Z, Wang Y, Ma Y, Li H, Zhang F, Wang W, Jia H, Li P, Li X, Wang Q, Ding Z, Dong H, Gu L, Li B. The YdiU Domain Modulates Bacterial Stress Signaling through Mn2+-Dependent UMPylation. Cell Rep. 2020 Sep 22;32(12):108161. doi: 10.1016/j.celrep.2020.108161.