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

Abstract

Lens epithelium-derived growth factor (LEDGF/p75) is an epigenetic reader and attractive therapeutic target involved in HIV integration and the development of mixed lineage leukaemia (MLL1) fusion-driven leukaemia. Besides HIV integrase and the MLL1-menin complex, LEDGF/p75 interacts with various cellular proteins via its integrase binding domain (IBD). Here we present structural characterization of IBD interactions with transcriptional repressor JPO2 and domesticated transposase PogZ, and show that the PogZ interaction is nearly identical to the interaction of LEDGF/p75 with MLL1. The interaction with the IBD is maintained by an intrinsically disordered IBD-binding motif (IBM) common to all known cellular partners of LEDGF/p75. In addition, based on IBM conservation, we identify and validate IWS1 as a novel LEDGF/p75 interaction partner. Our results also reveal how HIV integrase efficiently displaces cellular binding partners from LEDGF/p75. Finally, the similar binding modes of LEDGF/p75 interaction partners represent a new challenge for the development of selective interaction inhibitors.

LEDGF/p75 is dispensable for hematopoiesis but essential for MLL-rearranged leukemogenesis

“…Based on recent structural data, we mutated the IBD-interacting motif in MLL-ENL, which is responsible for the interaction with LEDGF/ p75. 45 CFU assays revealed impaired transformation capacity in lin 2 cells. These data corroborate the function of LEDGF/p75 in the tethering the MLL-FP, as has been suggested earlier.…”

“…In contrast to the p52 isoform, LEDGF/p75 contains the IBD domain, which specifically interacts with MLL and several other cellular proteins. 45 However, among these interaction partners, only MLL is known to affect HOX expression. Although we did not observe decreased expression of HoxA9 in the lin 2 fraction in contrast to other members of the HoxA cluster, our RNA-seq data revealed downregulation of HoxA9 targets in Psip1-depleted cells after 1 week in culture and that the observed phenotypes could be rescued upon HoxA9 overexpression suggests that the HoxA9 axis is an important component of the observed differentiation defects and decreased CFU formation.…”

“…In contrast, it has been recently suggested that LEDGF/p75 is required to tether the wild-type complex, but not MLL-FP at target gene loci. 24 To further investigate this, we introduced 2 mutations (F148A and F151A) in the consensus IBD-interacting motif 45 of the MLL-ENL fusion (mut.MLL-ENL) that specifically abrogate the interaction with LEDGF/p75 and evaluated its oncogenic activity in vitro. In contrast to the wild-type MLL-ENL fusion, the mut.MLL-ENL was unable to transform myeloid progenitors ( Figure 7F).…”

Lessons Learned: HIV Points the Way Towards Precision Treatment of Mixed-Lineage Leukemia

“…CDCA7L), IWS1 ('interacts with Spt6') and PogZ (pogo transposable element with zinc-finger domain) (Figure 1) [17][18][19][20][21][22][23]. With exception for the MLL/MENIN complex, the function of these cellular interactions or the reason for the recruitment of these proteins to active genes by LEDGF/ p75 is not yet understood.…”

“…A follow-up study revealed that all known cellular IBD interacting partners, including MLL, form a stable complex with the LEDGF/p75 IBD through an intrinsically disordered consensus motif ([E/D]-X-E-X-F-X-G-F), which is referred to as the IBD-binding motif (IBM) [21]. In conclusion, all currently known cellular IBD interaction partners carry an IBM, allowing LEDGF/p75 to tether them to the chromatin.…”