Solution structure of the R-module from AlgE4

Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 20 
  • Selection Criteria: target function 

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This is version 1.5 of the entry. See complete history


NMR structure of the R-module: a parallel beta-roll subunit from an Azotobacter vinelandii mannuronan C-5 epimerase.

Aachmann, F.L.Svanem, B.I.Guntert, P.Petersen, S.B.Valla, S.Wimmer, R.

(2006) J Biol Chem 281: 7350-7356

  • DOI: https://doi.org/10.1074/jbc.M510069200
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    In the bacterium Azotobacter vinelandii, a family of seven secreted and calcium-dependent mannuronan C-5 epimerases (AlgE1-7) has been identified. These epimerases are responsible for the epimerization of beta-d-mannuronic acid to alpha-l-guluronic acid in alginate polymers. The epimerases consist of two types of structural modules, designated A (one or two copies) and R (one to seven copies). The structure of the catalytically active A-module from the smallest epimerase AlgE4 (consisting of AR) has been solved recently. This paper describes the NMR structure of the R-module from AlgE4 and its titration with a substrate analogue and paramagnetic thulium ions. The R-module folds into a right-handed parallel beta-roll. The overall shape of the R-module is an elongated molecule with a positively charged patch that interacts with the substrate. Titration of the R-module with thulium indicated possible calcium binding sites in the loops formed by the nonarepeat sequences in the N-terminal part of the molecule and the importance of calcium binding for the stability of the R-module. Structure calculations showed that calcium ions can be incorporated in these loops without structural violations and changes. Based on the structure and the electrostatic surface potential of both the A- and R-module from AlgE4, a model for the appearance of the whole protein is proposed.

  • Organizational Affiliation

    Department of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Poly(beta-D-mannuronate) C5 epimerase 4167Azotobacter vinelandiiMutation(s): 0 
Gene Names: R-module subunit from algE4
EC: 5.1.3
Find proteins for Q44493 (Azotobacter vinelandii)
Explore Q44493 
Go to UniProtKB:  Q44493
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ44493
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 20 
  • Selection Criteria: target function 

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2006-01-10
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2020-02-26
    Changes: Data collection, Database references, Derived calculations, Other
  • Version 1.4: 2023-06-14
    Changes: Database references, Other
  • Version 1.5: 2024-05-15
    Changes: Data collection, Database references