Crystal structure of CBMd (family CBM41) from Eubacterium rectale Amy13K

Experimental Data Snapshot

  • Resolution: 2.20 Å
  • R-Value Free: 0.256 
  • R-Value Work: 0.232 
  • R-Value Observed: 0.234 

wwPDB Validation   3D Report Full Report

This is version 1.2 of the entry. See complete history


Novel carbohydrate binding modules in the surface anchored alpha-amylase of Eubacterium rectale provide a molecular rationale for the range of starches used by this organism in the human gut.

Cockburn, D.W.Suh, C.Medina, K.P.Duvall, R.M.Wawrzak, Z.Henrissat, B.Koropatkin, N.M.

(2018) Mol Microbiol 107: 249-264

  • DOI: https://doi.org/10.1111/mmi.13881
  • Primary Citation of Related Structures:  
    6AZ5, 6B15, 6B3P

  • PubMed Abstract: 

    Gut bacteria recognize accessible glycan substrates within a complex environment. Carbohydrate binding modules (CBMs) of cell surface glycoside hydrolases often drive binding to the target substrate. Eubacterium rectale, an important butyrate-producing organism in the gut, consumes a limited range of substrates, including starch. Host consumption of resistant starch increases the abundance of E. rectale in the intestine, likely because it successfully captures the products of resistant starch degradation by other bacteria. Here, we demonstrate that the cell wall anchored starch-degrading α-amylase, Amy13K of E. rectale harbors five CBMs that all target starch with differing specificities. Intriguingly these CBMs efficiently bind to both regular and high amylose corn starch (a type of resistant starch), but have almost no affinity for potato starch (another type of resistant starch). Removal of these CBMs from Amy13K reduces the activity level of the enzyme toward corn starches by ∼40-fold, down to the level of activity toward potato starch, suggesting that the CBMs facilitate activity on corn starch and allow its utilization in vivo. The specificity of the Amy13K CBMs provides a molecular rationale for why E. rectale is able to only use certain starch types without the aid of other organisms.

  • Organizational Affiliation

    Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
alpha-amylase116Agathobacter rectalis DSM 17629Mutation(s): 0 
Gene Names: EUR_21100
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.20 Å
  • R-Value Free: 0.256 
  • R-Value Work: 0.232 
  • R-Value Observed: 0.234 
  • Space Group: P 65 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 51α = 90
b = 51β = 90
c = 151.83γ = 120
Software Package:
Software NamePurpose
iMOSFLMdata reduction
Aimlessdata scaling

Structure Validation

View Full Validation Report

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
University of Michigan Gastrointestinal Peptides Research CenterUnited StatesDK034933
Department of Energy (DOE, United States)United StatesDE-AC02-06CH11357
Michigan Economic Development Corporation and the Michigan Technology Tri-CorridorUnited States085P1000817

Revision History  (Full details and data files)

  • Version 1.0: 2017-11-29
    Type: Initial release
  • Version 1.1: 2018-01-17
    Changes: Database references
  • Version 1.2: 2022-03-16
    Changes: Author supporting evidence, Database references