Germline BAP1 Inactivation Is Preferentially Associated with Metastatic Ocular Melanoma and Cutaneous-Ocular Melanoma Families

Background: BAP1 has been shown to be a target of both somatic alteration in high-risk ocular melanomas (OM) and germline inactivation in a few individuals from cancer-prone families. These findings suggest that constitutional BAP1 changes may predispose individuals to metastatic OM and that familial permeation of deleterious alleles could delineate a new cancer syndrome. Design: To characterize BAP1’s contribution to melanoma risk, we sequenced BAP1 in a set of 100 patients with OM, including 50 metastatic OM cases and 50 matched non-metastatic OM controls, and 200 individuals with cutaneous melanoma (CM) including 7 CM patients from CM-OM families and 193 CM patients from CM-non-OM kindreds. Results: Germline BAP1 mutations were detected in 4/50 patients with metastatic OM and 0/50 cases of non-metastatic OM (8 % vs. 0%, p = 0.059). Since 2/4 of the BAP1 carriers reported a family history of CM, we analyzed 200 additional hereditary CM patients and found mutations in 2/7 CM probands from CM-OM families and 1/193 probands from CM-non-OM kindreds (29 % vs. 0.52%, p =.003). Germline mutations co-segregated with both CM and OM phenotypes and were associated with the presence of unique nevoid melanomas and highly atypical nevoid melanoma-like melanocytic proliferations (NEMMPs). Interestingly, 7/14 germline variants identified to date reside in C-terminus suggesting that the BRCA1 binding domain i

Basis for a ubiquitin-like protein thioester switch toggling E1–E2 affinity

Ubiquitin-like proteins (UBLs) are conjugated by dynamic E1–E2–E3 enzyme cascades. E1 enzymes activate UBLs by catalysing UBL carboxy-terminal adenylation, forming a covalent E1~UBL thioester intermediate, and generating a thioester-linked E2~UBL product, which must be released for subsequent reactions. Here we report the structural analysis of a trapped UBL activation complex for the human NEDD8 pathway, containing NEDD8's heterodimeric E1 (APPBP1–UBA3), two NEDD8s (one thioester-linked to E1, one noncovalently associated for adenylation), a catalytically inactive E2 (Ubc12), and MgATP. The results suggest that a thioester switch toggles E1–E2 affinities. Two E2 binding sites depend on NEDD8 being thioester-linked to E1. One is unmasked by a striking E1 conformational change. The other comes directly from the thioester-bound NEDD8. After NEDD8 transfer to E2, reversion to an alternate E1 conformation would facilitate release of the E2~NEDD8 thioester product. Thus, transferring the UBL's thioester linkage between successive conjugation enzymes can induce conformational changes and alter interaction networks to drive consecutive steps in UBL cascades