Journal: bioRxiv
Article Title: Structural basis for the midnolin-proteasome pathway and its role in suppressing myeloma
doi: 10.1101/2025.02.22.639686
Figure Lengend Snippet: (A) Crystal structure of the EGR1-Catch fusion protein at 2.5 Å resolution. The interaction between EGR1 and the Catch domain is facilitated by alternating phenylalanine-glycine residues, forming an FG zipper. (B) Immunoblotting of anti-FLAG immunoprecipitates from HEK-293T cells expressing endogenous 3xHA-midnolin and transiently overexpressing EGR1-2xFLAG via a CMV promoter. Cells were treated with 10 µM MG132 for 4 hours. (C) AlphaFold-multimer prediction of the IRF4-midnolin complex shows an incomplete FG zipper, with valine 216 replacing tyrosine. The same immunoblot assay as in (b) was performed using cells transfected with 2xFLAG-IRF4. (D) AlphaFold-multimer prediction of the NeuroD1-midnolin interaction reveals an incomplete FG zipper, with isoleucine 279 replacing tyrosine and phenylalanine 285 sterically clashing with phenylalanine 280 of midnolin. The same assay as in (b) was conducted with cells transfected with 2xFLAG-NeuroD1. (E) AlphaFold-multimer prediction of SPINDOC-midnolin shows a missing FG zipper, with glycine 319, leucine 321, and leucine 323 substituting for tyrosine, glycine, and phenylalanine, respectively. The same assay as in (b) with cells transfected with 2xFLAG-SPINDOC. (F) The same assay as in (b) was performed using MIDN knockout HEK-293T cells reconstituted with either wild-type or zipper-swapped 2xHA-midnolin from a CMV promoter using lentivirus.
Article Snippet: Wild type and mutant versions of entry clones were subcloned into the following destination vectors via an LR reaction (Thermo Fisher Scientific, 11791100): pHAGE CMV 2xFLAG-destination vector for N-terminally tagging MIDN, IRF4, NeuroD1, and SPINDOC, a pHAGE CMV 2xHA-destination vector for N-terminally tagging PSMD2, a CMV-C-2xFLAG destination vector (Addgene, 118372) for C-terminally tagging EGR1, a pHAGE CMV 2xFLAG-MBP-destination vector for N-terminally tagging the midnolin α-HelixC, a GPS 3.0 destination vector for GFP-IRF4, a GPS 3.2 destination vector for EGR1-GFP, or a pHAGE EF1α-destination vector (blue fluorescent protein, BFP) for expressing untagged midnolin for flow cytometry experiments.
Techniques: Western Blot, Expressing, Transfection, Knock-Out