RCSB PDB - 8QFB: Crystal structure of human MPP8 C-terminal region (residues 565-860)

 8QFB

Crystal structure of human MPP8 C-terminal region (residues 565-860)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.04 Å
  • R-Value Free: 0.295 
  • R-Value Work: 0.256 
  • R-Value Observed: 0.258 

Starting Model: in silico
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wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Structure and Methyl-lysine Binding Selectivity of the HUSH Complex Subunit MPP8.

Nikolopoulos, N.Oda, S.I.Prigozhin, D.M.Modis, Y.

(2024) J Mol Biol 437: 168890-168890

  • DOI: https://doi.org/10.1016/j.jmb.2024.168890
  • Primary Citation of Related Structures:  
    8QFB

  • PubMed Abstract: 

    The Human Silencing Hub (HUSH) guards the genome from the pathogenic effects of retroelement expression. Composed of MPP8, TASOR, and Periphilin-1, HUSH recognizes actively transcribed retrotransposed sequences by the presence of long (>1.5-kb) nascent transcripts without introns. HUSH recruits effectors that alter chromatin structure, degrade transcripts, and deposit transcriptionally repressive epigenetic marks. Here, we report the crystal structure of the C-terminal domain (CTD) of MPP8 necessary for HUSH activity. The MPP8 CTD consists of five ankyrin repeats followed by a domain with structural homology to the PINIT domains of Siz/PIAS-family SUMO E3 ligases. AlphaFold3 modeling of the MPP8-TASOR complex predicts that a SPOC domain and a domain with a novel fold in TASOR form extended interaction interfaces with the MPP8 CTD. Point mutations at these interfaces resulted in loss of HUSH-dependent transcriptional repression in a cell-based reporter assay, validating the AlphaFold3 model. The MPP8 chromodomain, known to bind the repressive mark H3K9me3, bound with similar or higher affinity to sequences in the H3K9 methyltransferase subunits SETDB1, ATF7IP, G9a, and GLP. Hence, MPP8 promotes heterochromatinization by recruiting H3K9 methyltransferases. Our work identifies novel structural elements in MPP8 required for HUSH complex assembly and silencing, thereby fulfilling vital functions in controlling retrotransposons.


  • Organizational Affiliation

    Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK; Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Department of Medicine, University of Cambridge, Cambridge CB2 0AW, UK.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
M-phase phosphoprotein 8336Homo sapiensMutation(s): 0 
Gene Names: MPHOSPH8MPP8
UniProt & NIH Common Fund Data Resources
Find proteins for Q99549 (Homo sapiens)
Explore Q99549 
Go to UniProtKB:  Q99549
PHAROS:  Q99549
GTEx:  ENSG00000196199 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ99549
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.04 Å
  • R-Value Free: 0.295 
  • R-Value Work: 0.256 
  • R-Value Observed: 0.258 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 102.556α = 90
b = 179.531β = 90
c = 228.076γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
xia2data reduction
PHASERphasing
Aimlessdata scaling
Cootmodel building

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Wellcome TrustUnited Kingdom217191/Z/19/Z
Wellcome TrustUnited KingdomMX15916

Revision History  (Full details and data files)

  • Version 1.0: 2024-09-11
    Type: Initial release
  • Version 1.1: 2024-11-06
    Changes: Structure summary
  • Version 1.2: 2024-12-25
    Changes: Database references