Neuropathic mutations in MORC2 perturb GHKL ATPase dimerization dynamics and epigenetic silencing by multiple structural mechanisms

Douse, Christopher H.; Bloor, Stuart; Y, Liu; Shamin, Maria; Ia, Tchasovnikarova; Rt, Timms; Lehner, PJ; Modis, Yorgo

doi:10.1101/197186

Cited by 18 publications

(48 citation statements)

References 44 publications

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“…Structural comparison of the ATPase-CW cassette of MORC3 and the ATPase-CC-CW cassette of MORC2 (18) corroborates different mechanisms of action. Although the CW domains of both proteins are packed against the ATPase domains in a similar way, many ATPase:CW interfacial residues are not conserved and form distinct patterns of hydrogen bonding, electrostatic, and hydrophobic contacts ( Fig.…”

Section: Significancementioning

confidence: 63%

“…However, architecture of two other members of this family, MORC1 and MORC2, differ from that of MORC3/4. Recent biochemical and structural studies have shown that MORC2 has a distinctly different mechanism for targeting of chromatin (17,18). MORC2 contains a CW domain that does not bind to histone tails and a coiled-coil (CC) insertion between the ATPase domain and the CW domain that is involved in binding to DNA (16,18).…”

Section: Significancementioning

confidence: 99%

“…Recent biochemical and structural studies have shown that MORC2 has a distinctly different mechanism for targeting of chromatin (17,18). MORC2 contains a CW domain that does not bind to histone tails and a coiled-coil (CC) insertion between the ATPase domain and the CW domain that is involved in binding to DNA (16,18). In contrast to the mechanism by which MORC3 binds to chromatin and is activated, it has been demonstrated that following DNA damage, MORC2 is phosphorylated on Ser739, and this phosphorylation is required for the association of MORC2 with chromatin and its ATPase activity (17).…”

Section: Significancementioning

confidence: 99%

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Mechanism for autoinhibition and activation of the MORC3 ATPase

Zhang

Klein

Cox

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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Microrchidia 3 (MORC3) is a human protein linked to autoimmune disorders, Down syndrome, and cancer. It is a member of a newly identified family of human ATPases with an uncharacterized mechanism of action. Here, we elucidate the molecular basis for inhibition and activation of MORC3. The crystal structure of the MORC3 region encompassing the ATPase and CW domains in complex with a nonhydrolyzable ATP analog demonstrates that the two domains are directly coupled. The extensive ATPase:CW interface stabilizes the protein fold but inhibits the catalytic activity of MORC3. Enzymatic, NMR, mutational, and biochemical analyses show that in the autoinhibited, off state, the CW domain sterically impedes binding of the ATPase domain to DNA, which in turn is required for the catalytic activity. MORC3 autoinhibition is released by disrupting the intramolecular ATPase:CW coupling through the competitive interaction of CW with histone H3 tail or by mutating the interfacial residues. Binding of CW to H3 leads to a marked rearrangement in the ATPase–CW cassette, which frees the DNA-binding site in active MORC3 (on state). We show that ATP-induced dimerization of the ATPase domain is strictly required for the catalytic activity and that the dimeric form of ATPase–CW might cooperatively bind to dsDNA. Together, our findings uncovered a mechanism underlying the fine-tuned regulation of the catalytic domain of MORC3 by the epigenetic reader, CW.

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Section: Significancementioning

confidence: 63%

Section: Significancementioning

confidence: 99%

Section: Significancementioning

confidence: 99%

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Mechanism for autoinhibition and activation of the MORC3 ATPase

Zhang

Klein

Cox

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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“…The activity of TASOR is critical in early development: the homozygous mutation L130P, at a conserved leucine in mouse TASOR (identified as MommeD6), is lethal in embryos before gastrulation (Harten et al, 2014). The HUSH complex recruits the H3K9 methyltransferase SET domain bifurcated 1 (SETDB1) to deposit H3K9me3 (Tchasovnikarova et al, 2015) and the ATPase MORC2 to compact chromatin (Douse et al, 2018;Tchasovnikarova et al, 2017). HUSH is a vertebrate-specific chromatin regulator that represses both exogenous and endogenous genetic elements.…”

Section: Introductionmentioning

confidence: 99%

TASOR is a pseudo-PARP that directs HUSH complex assembly and epigenetic transposon control

Douse

Tchasovnikarova

Timms

et al. 2020

Preprint

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stability; histone H3 lysine 9 methylation (H3K9me3); transposable element (TE); long interspersed nuclear element-1 (LINE-1); poly-ADP ribose polymerase (PARP); RNA-binding protein; RNA-induced transcriptional silencing; CUT&RUN; CUT&Tag; genome profiling SummaryThe Human Silencing Hub (HUSH) complex epigenetically represses retroviruses, transposons and genes in vertebrates. HUSH therefore maintains genome integrity and is central in the interplay between intrinsic immunity, transposable elements and transcriptional regulation. Comprising three subunits -TASOR, MPP8 and Periphilin -HUSH regulates SETDB1-dependent deposition of the transcriptionally repressive epigenetic mark H3K9me3 and recruits MORC2 to modify local chromatin structure. However the mechanistic roles of each HUSH subunit remain undetermined. Here we show that TASOR lies at the heart of HUSH, providing a platform for assembling the other subunits. Targeted epigenomic profiling supports the model that TASOR binds and regulates H3K9me3 specifically over LINE-1 repeats and other repetitive exons in transcribed genes. We find TASOR associates with several components of the nuclear RNA processing machinery and its modular domain architecture bears striking similarities to that of Chp1, the central component of the yeast RNA-induced transcriptional silencing (RITS) complex. Together these observations suggest that an RNA intermediate may be important for HUSH activity. We identify the TASOR domains necessary for HUSH assembly and transgene repression. Structural and genomic analyses reveal that TASOR contains a poly-ADP ribose polymerase (PARP) domain dispensable for assembly and chromatin localization, but critical for epigenetic regulation of target elements. This domain contains a degenerated and obstructed active site and has hence lost catalytic activity. Together our data demonstrate that TASOR is a pseudo-PARP critical for HUSH complex assembly and H3K9me3 deposition over its genomic targets.

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“…For example, TE-derived proteins catalyze V(D)J recombination (Zhou et al, 2004) and H3 lysine 9 trimethylation (H3K9me3), a transcriptionally repressive mark, through recruitment of the H3K9 methyltransferase SETDB1 and its stabilizing factor ATF7IP (Tchasovnikarova et al, 2015;Timms et al, 2016). HUSH silencing also requires MORC2, a DNA-binding ATPase that acts as a chromatin remodeler (Douse et al, 2018;Tchasovnikarova et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Periphilin self-association underpins epigenetic silencing by the HUSH complex

Prigozhin

Albecka

Douse

et al. 2019

Preprint

Self Cite

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Transcription of integrated DNA from viruses or transposable elements is tightly regulated to prevent pathogenesis. The Human Silencing Hub (HUSH), composed of Periphilin, TASOR and MPP8, silences transcriptionally active viral and endogenous transgenes. HUSH recruits effectors that alter the epigenetic landscape and chromatin structure, but how HUSH recognizes target loci and represses their expression remains unclear. We identify the physicochemical properties of Periphilin necessary for HUSH assembly and silencing. A disordered N-terminal domain (NTD) and structured C-terminal domain are essential for silencing. A crystal structure of the Periphilin-TASOR core complex shows Periphilin forms a-helical homodimers, which each bind a single TASOR molecule. The NTD binds RNA non-specifically and forms insoluble aggregates through an arginine/tyrosine-rich sequence reminiscent of low-complexity regions from self-associating RNA-binding proteins. Residues required for TASOR binding and aggregation were required for HUSH-dependent silencing and genome-wide deposition of repressive mark H3K9me3. The NTD was functionally complemented by low-complexity regions from certain RNA-binding proteins and proteins that form condensates or fibrils. Our work suggests the associative properties of Periphilin promote HUSH aggregation on nascent transcripts. Running title: Function of Periphilin in HUSH silencingKeywords: Transcriptional repression; epigenetic silencing; histone H3 lysine 9 methylation (H3K9me3); transposable element (TE); long interspersed nuclear element-1 (LINE-1); lowcomplexity sequence; disordered region; arginine/tyrosine-rich region; biomolecular condensate; liquid phase separation; membraneless compartment; RNA-binding protein syncytiotrophoblast fusion in placental development (Dupressoir et al, 2012;Friedli & Trono, 2015).A subset of TEs can autonomously replicate through an RNA intermediate and reintegrate into the genome like retroviruses. Some of these TEs are endogenous retrovirus (ERV) genomes inherited from ancestral infections of germline. The other type of autonomously replicating TE in humans are the non-viral LINE-1 (long interspersed nuclear element-1) retroelements. Active ERVs and LINE-1s are transcribed and encode reverse transcriptase and integrase enzymes,

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Neuropathic mutations in MORC2 perturb GHKL ATPase dimerization dynamics and epigenetic silencing by multiple structural mechanisms

Cited by 18 publications

References 44 publications

Mechanism for autoinhibition and activation of the MORC3 ATPase

Mechanism for autoinhibition and activation of the MORC3 ATPase

TASOR is a pseudo-PARP that directs HUSH complex assembly and epigenetic transposon control

Periphilin self-association underpins epigenetic silencing by the HUSH complex

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