6N8C

Structure of the Huntingtin tetramer/dimer mixture determined by paramagnetic NMR


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 1100 
  • Conformers Submitted: 10 
  • Selection Criteria: structures with the lowest energy 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Probing initial transient oligomerization events facilitating Huntingtin fibril nucleation at atomic resolution by relaxation-based NMR.

Kotler, S.A.Tugarinov, V.Schmidt, T.Ceccon, A.Libich, D.S.Ghirlando, R.Schwieters, C.D.Clore, G.M.

(2019) Proc Natl Acad Sci U S A 116: 3562-3571

  • DOI: 10.1073/pnas.1821216116
  • Primary Citation of Related Structures:  
    6N8C

  • PubMed Abstract: 
  • The N-terminal region of the huntingtin protein, encoded by exon-1, comprises an amphiphilic domain (htt NT ), a polyglutamine (Q n ) tract, and a proline-rich sequence. Polyglutamine expansion results in an aggregation-prone protein responsible for Huntington's disease ...

    The N-terminal region of the huntingtin protein, encoded by exon-1, comprises an amphiphilic domain (htt NT ), a polyglutamine (Q n ) tract, and a proline-rich sequence. Polyglutamine expansion results in an aggregation-prone protein responsible for Huntington's disease. Here, we study the earliest events involved in oligomerization of a minimalistic construct, htt NT Q 7 , which remains largely monomeric over a sufficiently long period of time to permit detailed quantitative NMR analysis of the kinetics and structure of sparsely populated [Formula: see text] oligomeric states, yet still eventually forms fibrils. Global fitting of concentration-dependent relaxation dispersion, transverse relaxation in the rotating frame, and exchange-induced chemical shift data reveals a bifurcated assembly mechanism in which the NMR observable monomeric species either self-associates to form a productive dimer (τ ex ∼ 30 μs, K diss ∼ 0.1 M) that goes on to form a tetramer ([Formula: see text] μs; K diss ∼ 22 μM), or exchanges with a "nonproductive" dimer that does not oligomerize further (τ ex ∼ 400 μs; K diss ∼ 0.3 M). The excited state backbone chemical shifts are indicative of a contiguous helix (residues 3-17) in the productive dimer/tetramer, with only partial helical character in the nonproductive dimer. A structural model of the productive dimer/tetramer was obtained by simulated annealing driven by intermolecular paramagnetic relaxation enhancement data. The tetramer comprises a D 2 symmetric dimer of dimers with largely hydrophobic packing between the helical subunits. The structural model, validated by EPR distance measurements, illuminates the role of the htt NT domain in the earliest stages of prenucleation and oligomerization, before fibril formation.


    Organizational Affiliation

    Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520; mariusc@mail.nih.gov.



Macromolecules

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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
HuntingtinA, B, C, D23Homo sapiensMutation(s): 0 
Gene Names: HTTHDIT15
UniProt & NIH Common Fund Data Resources
Find proteins for P42858 (Homo sapiens)
Explore P42858 
Go to UniProtKB:  P42858
PHAROS:  P42858
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP42858
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 1100 
  • Conformers Submitted: 10 
  • Selection Criteria: structures with the lowest energy 

Structure Validation

View Full Validation Report



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United States1FI2GM117609-01

Revision History  (Full details and data files)

  • Version 1.0: 2019-02-13
    Type: Initial release
  • Version 1.1: 2019-03-13
    Changes: Data collection, Database references
  • Version 1.2: 2020-01-01
    Changes: Author supporting evidence, Data collection