Solution structure of the R-module from AlgE4Solution structure of the R-module from AlgE4

Structural highlights

2agm is a 1 chain structure with sequence from Azotobacter vinelandii. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:Solution NMR
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

ALGE4_AZOVI Converts beta-D-mannuronic acid (M) to alpha-L-guluronic acid (G), but introduces almost exclusively MG blocks, producing a polymer with non-gel-forming capacity.

Evolutionary Conservation

 

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

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.

NMR structure of the R-module: a parallel beta-roll subunit from an Azotobacter vinelandii mannuronan C-5 epimerase.,Aachmann FL, Svanem BI, Guntert P, Petersen SB, Valla S, Wimmer R J Biol Chem. 2006 Mar 17;281(11):7350-6. Epub 2006 Jan 3. PMID:16407237[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

  1. Aachmann FL, Svanem BI, Guntert P, Petersen SB, Valla S, Wimmer R. NMR structure of the R-module: a parallel beta-roll subunit from an Azotobacter vinelandii mannuronan C-5 epimerase. J Biol Chem. 2006 Mar 17;281(11):7350-6. Epub 2006 Jan 3. PMID:16407237 doi:10.1074/jbc.M510069200
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