The same pocket in menin binds both MLL and JUND but has opposite effects on transcription

Abstract

Menin is a tumor suppressor protein whose loss or inactivation causes multiple endocrine neoplasia type 1 (MEN1), a hereditary autosomal dominant tumor syndrome characterized by tumorigenesis in multiple endocrine organs1. Menin interacts with a multitude of proteins and involves in a variety of cellular processes2–6. Menin binds the Jun family transcription factor JunD and inhibits its transcriptional activity7,8. Several MEN1 missense mutations disrupted the menin-JunD interaction suggestive of a correlation between menin’s tumor suppressor function and its interaction with JunD and suppression of JunD activated transcription8,9. Menin also interacts with mixed lineage leukemia protein 1 MLL1, a histone H3 lysine 4 (H3K4) methyltransferase, and functions as an oncogenic cofactor to upregulate gene (including HOX genes) transcription and promote MLL1 fusion protein (MFP)-induced leukemogenesis10–12. A recent report on menin tethering MLL1 to chromatin binding factor LEDGF indicates menin as a molecular adaptor to coordinate the functions of multiple proteins13. Despite the importance of menin, it still remains poorly understood how menin could interact with many distinct partners and control multiple functions. Here we present the crystal structures of menin, free and in complexes with MLL1 or JunD, or an MLL1-LEDGF heterodimer. These structures show that menin contains a deep pocket that binds short peptides of MLL1 or JunD in the same manner, but oppositely regulates transcription. The menin-JunD interaction blocks JNK kinase-meidated JunD phosphorylation, a crucial event for JunD activation.Moreover, menin functions as a scaffold molecule to promote gene transcription by binding MLL1 through the peptide-pocket yet interacting with LEDGF at a distinct surface.

Multiple cellular proteins interact with LEDGF/p75 through a conserved unstructured consensus motif

“…To interpret the changes in the IBD signal positions, we acquired essentially complete sequence-specific backbone resonance assignment of 13 C/ 15 N-labelled IBD using a set of standard triple-resonance NMR experiments. We assigned 95.4% of 1 H, 15 N, 13 C 0 and 13 C a/ b atoms of the IBD. Backbone amide signals ( 15 N and 1 H) were assigned for all residues except for four amino acids (E345, M348, Q410 and T417).…”

“…To gain further insight into the topology of these specific changes, we carried out sequence-specific backbone resonance assignment of 13 C/ 15 N-labelled JPO2 and PogZ 1117-1410 using a set of standard triple-resonance NMR experiments. We assigned 94.4% of 1 H, 15 N, 13 C 0 and 13 C a/b atoms of JPO2 . For PogZ 1117-1410 , we were able to assign essentially all 1 H, 15 N, 13 C 0 and 13 C a/b signals of an apparently unstructured C-terminal region (residues 1,368-1,410) that was significantly affected by IBD binding.…”

“…We assigned 94.4% of 1 H, 15 N, 13 C 0 and 13 C a/b atoms of JPO2 . For PogZ 1117-1410 , we were able to assign essentially all 1 H, 15 N, 13 C 0 and 13 C a/b signals of an apparently unstructured C-terminal region (residues 1,368-1,410) that was significantly affected by IBD binding.…”

“…The effects of complex formation on individual amino-acid residues of JPO2 and PogZ 1117-1410 were quantified as minimal chemical shift values in backbone resonances ( 15 N, 13 C 0 and 1 H N ) divided by corresponding s.d. (Fig.…”

“…The LEDGF/p75-MLL1-menin complex has been structurally characterized, but the published X-ray data revealed only part of the ternary complex (PDB ID 3U88 (ref. 13)). Recently, we and others identified a second menin-independent MLL1 binding site on LEDGF/p75 (refs 14,15).…”