Alpha-1-antitrypsin - Sydney variant (G192C)

Experimental Data Snapshot

  • Resolution: 1.91 Å
  • R-Value Free: 0.253 
  • R-Value Work: 0.210 
  • R-Value Observed: 0.212 

wwPDB Validation   3D Report Full Report

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A novel pathological mutant reveals the role of torsional flexibility in the serpin breach in adoption of an aggregation-prone intermediate.

Kamuda, K.Ronzoni, R.Majumdar, A.Guan, F.H.X.Irving, J.A.Lomas, D.A.

(2024) FEBS J 

  • DOI: https://doi.org/10.1111/febs.17121
  • Primary Citation of Related Structures:  
    8P4J, 8P4U

  • PubMed Abstract: 

    Mutants of alpha-1-antitrypsin cause the protein to self-associate and form ordered aggregates ('polymers') that are retained within hepatocytes, resulting in a predisposition to the development of liver disease. The associated reduction in secretion, and for some mutants, impairment of function, leads to a failure to protect lung tissue against proteases released during the inflammatory response and an increased risk of emphysema. We report here a novel deficiency mutation (Gly192Cys), that we name the Sydney variant, identified in a patient in heterozygosity with the Z allele (Glu342Lys). Cellular analysis revealed that the novel variant was mostly retained as insoluble polymers within the endoplasmic reticulum. The basis for this behaviour was investigated using biophysical and structural techniques. The variant showed a 40% reduction in inhibitory activity and a reduced stability as assessed by thermal unfolding experiments. Polymerisation involves adoption of an aggregation-prone intermediate and paradoxically the energy barrier for transition to this state was increased by 16% for the Gly192Cys variant with respect to the wild-type protein. However, with activation to the intermediate state, polymerisation occurred at a 3.8-fold faster rate overall. X-ray crystallography provided two crystal structures of the Gly192Cys variant, revealing perturbation within the 'breach' region with Cys192 in two different orientations: in one structure it faces towards the hydrophobic core while in the second it is solvent-exposed. This orientational heterogeneity was confirmed by PEGylation. These data show the critical role of the torsional freedom imparted by Gly192 in inhibitory activity and stability against polymerisation.

  • Organizational Affiliation

    Division of Medicine, UCL Respiratory, Rayne Institute, University College London, UK.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Alpha-1-antitrypsin400Homo sapiensMutation(s): 1 
UniProt & NIH Common Fund Data Resources
Find proteins for P01009 (Homo sapiens)
Explore P01009 
Go to UniProtKB:  P01009
PHAROS:  P01009
GTEx:  ENSG00000197249 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP01009
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.91 Å
  • R-Value Free: 0.253 
  • R-Value Work: 0.210 
  • R-Value Observed: 0.212 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 114.061α = 90
b = 38.544β = 104.62
c = 89.992γ = 90
Software Package:
Software NamePurpose
Aimlessdata scaling
autoPROCdata reduction

Structure Validation

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Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Medical Research Council (MRC, United Kingdom)United KingdomMR/V0342434/1
Wellcome TrustUnited Kingdom219939/Z/19/Z

Revision History  (Full details and data files)

  • Version 1.0: 2024-04-03
    Type: Initial release