Diabetes mellitus due to a frustrated Schellman motif in HNF-1a

Experimental Data Snapshot

  • Resolution: 1.40 Å
  • R-Value Free: 0.288 
  • R-Value Work: 0.228 
  • R-Value Observed: 0.230 

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This is version 1.5 of the entry. See complete history


Diabetes mellitus due to misfolding of a beta-cell transcription factor: stereospecific frustration of a Schellman motif in HNF-1alpha.

Narayana, N.Phillips, N.B.Hua, Q.X.Jia, W.Weiss, M.A.

(2006) J Mol Biol 362: 414-429

  • DOI: https://doi.org/10.1016/j.jmb.2006.06.086
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Maturity-onset diabetes of the young (MODY3), a monogenic form of type II diabetes mellitus, results most commonly from mutations in hepatocyte nuclear factor 1alpha (HNF-1alpha). Diabetes-associated mutation G20R perturbs the dimerization domain of HNF-1alpha, an intertwined four-helix bundle. In the wild-type structure G20 participates in a Schellman motif to cap an alpha-helix; its dihedral angles lie in the right side of the Ramachandran plot (alpha(L) region; phi 97 degrees). Substitutions G20R and G20A lead to dimeric molten globules of low stability, suggesting that the impaired function of the diabetes-associated transcription factor is due in large part to a main-chain perturbation rather than to specific features of the Arg side-chain. This hypothesis is supported by the enhanced stability of non-standard analogues containing D-Ala or D-Ser at position 20. The crystal structure of the D-Ala20 analogue, determined to a resolution of 1.4 A, is essentially identical to the wild-type structure in the same crystal form. The mean root-mean-square deviation between equivalent C(alpha) atoms (residues 5-28) is 0.3 A; (phi, psi) angles of D-Ala20 are the same as those of G20 in the wild-type structure. Whereas the side-chain of A20 or R20 would be expected to clash with the preceding carbonyl oxygen (thus accounting for its frustrated energy landscape), the side-chain of D-Ala20 projects into solvent without perturbation of the Schellman motif. Calorimetric studies indicate that the increased stability of the D-Ala20 analogue (DeltaDeltaG(u) 1.5 kcal/mol) is entropic in origin, consistent with a conformational bias toward native-like conformations in the unfolded state. Studies of multiple substitutions at G20 and neighboring positions highlight the essential contributions of a glycine-specific tight turn and adjoining inter-subunit side-chain hydrogen bonds to the stability and architectural specificity of the intertwined dimer. Comparison of L- and D amino acid substitutions thus provides an example of the stereospecific control of an energy landscape by a helix-capping residue.

  • Organizational Affiliation

    Department of Biochemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4935, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Hepatocyte nuclear factor 1-alpha
A, B
33N/AMutation(s): 1 
UniProt & NIH Common Fund Data Resources
Find proteins for P20823 (Homo sapiens)
Explore P20823 
Go to UniProtKB:  P20823
PHAROS:  P20823
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP20823
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 0 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
Query on NLE
A, B
Experimental Data & Validation

Experimental Data

  • Resolution: 1.40 Å
  • R-Value Free: 0.288 
  • R-Value Work: 0.228 
  • R-Value Observed: 0.230 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 29.18α = 90
b = 42.95β = 90
c = 42.37γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
ADSCdata collection

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-03-20
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2019-07-24
    Changes: Data collection, Derived calculations, Refinement description
  • Version 1.4: 2023-08-30
    Changes: Data collection, Database references, Refinement description
  • Version 1.5: 2023-11-15
    Changes: Data collection