BS69/ZMYND11 C-Terminal Domains Bind and Inhibit EBNA2

Abstract

Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA2) plays an important role in driving immortalization of EBV-infected B cells through regulating the expression of many viral and cellular genes. We report a structural study of the tumor suppressor BS69/ZMYND11 C-terminal region, comprised of tandem coiled-coil-MYND domains (BS69CC-MYND), in complex with an EBNA2 peptide containing a PXLXP motif. The coiled-coil domain of BS69 self-associates to bring two separate MYND domains in close proximity, thereby enhancing the BS69 MYND-EBNA2 interaction. ITC analysis of BS69CC-MYND with a C-terminal fragment of EBNA2 further suggests that the BS69CC-MYND homodimer synergistically binds to the two EBNA2 PXLXP motifs that are respectively located in the conserved regions CR7 and CR8. Furthermore, we showed that EBNA2 interacts with BS69 and down-regulates its expression at both mRNA and protein levels in EBV-infected B cells. Ectopic BS69CC-MYND is recruited to viral target promoters through interactions with EBNA2, inhibits EBNA2-mediated transcription activation, and impairs proliferation of lymphoblastoid cell lines (LCLs). Substitution of critical residues in the MYND domain impairs the BS69-EBNA2 interaction and abolishes the BS69 inhibition of the EBNA2-mediated transactivation and LCL proliferation. This study identifies the BS69 C-terminal domains as an inhibitor of EBNA2, which may have important implications in development of novel therapeutic strategies against EBV infection.

The Transcriptional Repressor BS69 is a Conserved Target of the E1A Proteins from Several Human Adenovirus Species

“…Interestingly, substituting P117, the second proline of the highly conserved PXLXP motif with alanine did not negatively affect this interaction. Our observations agreed with results from a previous study, where residues in EBV EBNA2 analogous to E1A P113 and L115 were found to form hydrogen bonds with BS69, while the equivalent EBNA2 residue to E1A P117 only formed weaker van der Waals contacts [25]. Therefore, the P117A mutation may not be as detrimental since the replacement alanine residue may also form van der Waals contacts in a similar manner.…”

“…BS69 was initially discovered as a HAdV-C5 E1A interacting protein and reported to function as a strong inhibitor of E1A-dependent transactivation [22]. This 69 kDa protein is 602 residues in length, localizes to the nucleus, is ubiquitously expressed, and carries out a variety of functions associated with gene regulation [25,26,27,28]. BS69 is composed of four previously described domains.…”

“…In this case, BS69 binds to and inhibits transactivation by ETS2, but does not bind nor affect ETS1 dependent activation [36]. Furthermore, EBNA2, a transcriptional activator encoded by Epstein-Barr virus (EBV), binds BS69 via two PXLXP motifs and is similarly repressed by BS69 [25]. Data from those studies indicate that although the core PXLXP motif is necessary in mediating an interaction with BS69, additional residues in and around this core motif also appear crucial for interaction.…”

Transcription factors operate across disease loci, with EBNA2 implicated in autoimmunity

“…Notably, four of the top 20 TFs that co-occupy EBNA2 disorder loci with EBNA2 can be targeted by at least one available drug (MED1, p300, NFKB1, and NFKB2) 45 , and a recent study shows that the C-terminal domain of the BS69/ZMYND11 protein can bind to and inhibit EBNA2 46 . These results offer promise for the development of future therapies for manipulating the action of these proteins in individuals harboring risk alleles at EBNA2-bound loci.…”

Mga Modulates Bmpr1a Activity by Antagonizing Bs69 in Zebrafish

“…BS69 (ZMYND11) is a multidomain-containing (i.e., PHD, BROMO, PWWP, and MYND) protein that was originally identified as an adenoviral early region 1A-interacting protein ( Ansieau and Leutz, 2002 ; Harter et al, 2016 ). Through its PHD–BROMO–PWWP domains, BS69 selectively recognizes histone variant H3.3 lysine 36 trimethylation (H3.3K36me3), modulates RNA Polymerase II elongation, and functions as RNA splicing regulator for intron retention ( Guo et al, 2014 ; Wen et al, 2014 ).…”