Crystal structure of Family 31 alpha-glucosidase (BT_0339) from Bacteroides thetaiotaomicron

Experimental Data Snapshot

  • Resolution: 2.60 Å
  • R-Value Free: 0.349 
  • R-Value Work: 0.302 
  • R-Value Observed: 0.304 

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Suggested alternative starch utilization system from the human gut bacterium Bacteroides thetaiotaomicron.

Chaudet, M.M.Rose, D.R.

(2016) Biochem Cell Biol 94: 241-246

  • DOI: https://doi.org/10.1139/bcb-2016-0002
  • Primary Citation of Related Structures:  
    5DJW, 5F7C

  • PubMed Abstract: 

    The human digestive system is host to a highly populated ecosystem of bacterial species that significantly contributes to our assimilation of dietary carbohydrates. Bacteroides thetaiotaomicron is a member of this ecosystem, and participates largely in the role of the gut microbiome by breaking down dietary complex carbohydrates. This process of acquiring glycans from the colon lumen is predicted to rely on the mechanisms of proteins that are part of a classified system known as polysaccharide utilization loci (PUL). These loci are responsible for binding substrates at the cell outer membrane, internalizing them, and then hydrolyzing them within the periplasm into simple sugars. Here we report our investigation into specific components of a PUL, and suggest an alternative starch utilization system in B. thetaiotaomicron. Our analysis of an outer membrane binding protein, a SusD homolog, highlights its contribution to this PUL by acquiring starch-based sugars from the colon lumen. Through our structural characterization of two Family GH31 α-glucosidases, we reveal the flexibility of this bacterium with respect to utilizing a range of starch-derived glycans with an emphasis on branched substrates. With these results we demonstrate the predicted function of a gene locus that is capable of contributing to starch hydrolysis in the human colon.

  • Organizational Affiliation

    University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B, C, D
761Bacteroides thetaiotaomicron VPI-5482Mutation(s): 0 
Gene Names: BT_0339
Find proteins for Q8AAX3 (Bacteroides thetaiotaomicron (strain ATCC 29148 / DSM 2079 / JCM 5827 / CCUG 10774 / NCTC 10582 / VPI-5482 / E50))
Explore Q8AAX3 
Go to UniProtKB:  Q8AAX3
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8AAX3
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.60 Å
  • R-Value Free: 0.349 
  • R-Value Work: 0.302 
  • R-Value Observed: 0.304 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 82.34α = 90
b = 75β = 95.14
c = 232.86γ = 90
Software Package:
Software NamePurpose
PDB_EXTRACTdata extraction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2016-02-17
    Type: Initial release
  • Version 1.1: 2018-05-16
    Changes: Data collection, Database references, Derived calculations
  • Version 1.2: 2024-03-06
    Changes: Data collection, Database references