1NP0

Human lysosomal beta-hexosaminidase isoform B in complex with intermediate analogue NAG-thiazoline

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.227 
  • R-Value Work: 0.198 
  • R-Value Observed: 0.200 

wwPDB Validation 3D Report Full Report



Literature

Crystal structure of Human beta-hexosaminidase B: Understanding the molecular basis of Sandhoff and Tay-Sachs disease

Mark, B.L., Mahuran, D.J., Cherney, M.M., Zhao, D., Knapp, S., James, M.N.G.

(2003) J Mol Biol 327: 1093-1109

  • DOI: 10.1016/s0022-2836(03)00216-x
  • Primary Citation of Related Structures:  
    1NP0, 1NOW, 1NOU

  • PubMed Abstract: 

    • In humans, two major beta-hexosaminidase isoenzymes exist: Hex A and Hex B. Hex A is a heterodimer of subunits alpha and beta (60% identity), whereas Hex B is a homodimer of beta-subunits. Interest in human beta-hexosaminidase stems from its associat ...

    In humans, two major beta-hexosaminidase isoenzymes exist: Hex A and Hex B. Hex A is a heterodimer of subunits alpha and beta (60% identity), whereas Hex B is a homodimer of beta-subunits. Interest in human beta-hexosaminidase stems from its association with Tay-Sachs and Sandhoff disease; these are prototypical lysosomal storage disorders resulting from the abnormal accumulation of G(M2)-ganglioside (G(M2)). Hex A degrades G(M2) by removing a terminal N-acetyl-D-galactosamine (beta-GalNAc) residue, and this activity requires the G(M2)-activator, a protein which solubilizes the ganglioside for presentation to Hex A. We present here the crystal structure of human Hex B, alone (2.4A) and in complex with the mechanistic inhibitors GalNAc-isofagomine (2.2A) or NAG-thiazoline (2.5A). From these, and the known X-ray structure of the G(M2)-activator, we have modeled Hex A in complex with the activator and ganglioside. Together, our crystallographic and modeling data demonstrate how alpha and beta-subunits dimerize to form either Hex A or Hex B, how these isoenzymes hydrolyze diverse substrates, and how many documented point mutations cause Sandhoff disease (beta-subunit mutations) and Tay-Sachs disease (alpha-subunit mutations).

    Organizational Affiliation: 

    Canadian Institutes of Heath Research Group in Protein Structure and Function, Department of Biochemistry, University of Alberta, T6G 2H7, Edmonton, Alt., Canada.



Macromolecules
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(by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Beta-hexosaminidase subunit betaA, B58Homo sapiensMutation(s): 0 
Gene Names: HEXB, HCC7
EC: 3.2.1.52
Find proteins for P07686 (Homo sapiens)
Explore P07686 
Go to UniProtKB:  P07686
NIH Common Fund Data Resources
PHAROS  P07686
GTEx  ENSG00000049860
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  • Reference Sequence
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(by identity cutoff)  |  Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Beta-hexosaminidase subunit beta chain BC, E190Homo sapiensMutation(s): 0 
Gene Names: HEXB, HCC7
EC: 3.2.1.52
Find proteins for P07686 (Homo sapiens)
Explore P07686 
Go to UniProtKB:  P07686
NIH Common Fund Data Resources
PHAROS  P07686
GTEx  ENSG00000049860
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  • Reference Sequence
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(by identity cutoff)  |  Structure
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Beta-hexosaminidase subunit beta chain AD, F241Homo sapiensMutation(s): 0 
Gene Names: HEXB, HCC7
EC: 3.2.1.52
Find proteins for P07686 (Homo sapiens)
Explore P07686 
Go to UniProtKB:  P07686
NIH Common Fund Data Resources
PHAROS  P07686
GTEx  ENSG00000049860
Protein Feature View
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  • Reference Sequence
Oligosaccharides

Help

Entity ID: 4
MoleculeChainsChain Length2D Diagram Glycosylation
2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose
G, H
2 N-Glycosylation
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NGT
Query on NGT
Download CCD File 
A, B
3AR,5R,6S,7R,7AR-5-HYDROXYMETHYL-2-METHYL-5,6,7,7A-TETRAHYDRO-3AH-PYRANO[3,2-D]THIAZOLE-6,7-DIOL
C8 H13 N O4 S
DRHXTSWSUAJOJZ-FMDGEEDCSA-N		 Ligand Interaction
SO4
Query on SO4
Download CCD File 
B
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L		 Ligand Interaction
GOL
Query on GOL
Download CCD File 
A, B
GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N		 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
NGTKi :  270000   nM  PDBBind
NGTKi:  290   nM  BindingDB
NGTKi:  270000   nM  BindingDB
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.227 
  • R-Value Work: 0.198 
  • R-Value Observed: 0.200 
  • Space Group: P 61 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 112.414α = 90
b = 112.414β = 90
c = 397.232γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2003-04-29
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Advisory, Derived calculations, Version format compliance
  • Version 2.0: 2017-08-16
    Changes: Advisory, Atomic model, Database references, Derived calculations, Polymer sequence, Source and taxonomy, Structure summary
  • Version 3.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Data collection, Derived calculations, Structure summary