2AGM

Solution structure of the R-module from AlgE4

Summary for 2AGM

• Entry DOI: 10.2210/pdb2agm/pdb
• NMR Information: BMRB: 6390
• Descriptor: Poly(beta-D-mannuronate) C5 epimerase 4 (1 entity in total)
• Functional Keywords: parallel beta-roll, isomerase
• Biological source: Azotobacter vinelandii
• Total number of polymer chains: 1
• Total formula weight: 16976.01

Authors

Aachmann, F.L.,Svanem, B.I.,Guntert, P.,Petersen, S.B.,Valla, S.,Wimmer, R. (deposition date: 2005-07-27, release date: 2006-01-10, Last modification date: 2024-05-15)

Primary citation

Aachmann, F.L.,Svanem, B.I.,Guntert, P.,Petersen, S.B.,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., 281:7350-7356, 2006

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.

PubMed: 16407237
DOI: 10.1074/jbc.M510069200

Experimental method

SOLUTION NMR