2ML3

Solution Structure of AlgE6R3 subunit from the Azotobacter vinelandii Mannuronan C5-epimerase

Summary for 2ML3

• Entry DOI: 10.2210/pdb2ml3/pdb
• Related: 2AGM 2ML1 2ML2 2PYG 2PYH
• NMR Information: BMRB: 16956
• Descriptor: Poly(beta-D-mannuronate) C5 epimerase 6, CALCIUM ION (2 entities in total)
• Functional Keywords: alginate c-5 epimerase, mannuronan c-5 epimerase, r-module, isomerase
• Biological source: Azotobacter vinelandii
• Cellular location: Secreted, extracellular space: Q9ZFH0
• Total number of polymer chains: 1
• Total formula weight: 18477.91

Authors

Buchinger, E.,Wimmer, R.,Aachmann, F.L. (deposition date: 2014-02-18, release date: 2014-10-01, Last modification date: 2024-05-15)

Primary citation

Buchinger, E.,Knudsen, D.H.,Behrens, M.A.,Pedersen, J.S.,Aarstad, O.A.,Tndervik, A.,Valla, S.,Skjak-Brk, G.,Wimmer, R.,Aachmann, F.L.
Structural and Functional Characterization of the R-modules in Alginate C-5 Epimerases AlgE4 and AlgE6 from Azotobacter vinelandii
J.Biol.Chem., 289:31382-31396, 2014

PubMed Abstract: The bacterium Azotobacter vinelandii produces a family of seven secreted and calcium-dependent mannuronan C-5 epimerases (AlgE1-7). These epimerases are responsible for the epimerization of β-D-mannuronic acid (M) to α-L-guluronic acid (G) in alginate polymers. The epimerases display a modular structure composed of one or two catalytic A-modules and from one to seven R-modules having an activating effect on the A-module. In this study, we have determined the NMR structure of the three individual R-modules from AlgE6 (AR1R2R3) and the overall structure of both AlgE4 (AR) and AlgE6 using small angle x-ray scattering. Furthermore, the alginate binding ability of the R-modules of AlgE4 and AlgE6 has been studied with NMR and isothermal titration calorimetry. The AlgE6 R-modules fold into an elongated parallel β-roll with a shallow, positively charged groove across the module. Small angle x-ray scattering analyses of AlgE4 and AlgE6 show an overall elongated shape with some degree of flexibility between the modules for both enzymes. Titration of the R-modules with defined alginate oligomers shows strong interaction between AlgE4R and both oligo-M and MG, whereas no interaction was detected between these oligomers and the individual R-modules from AlgE6. A combination of all three R-modules from AlgE6 shows weak interaction with long M-oligomers. Exchanging the R-modules between AlgE4 and AlgE6 resulted in a novel epimerase called AlgE64 with increased G-block forming ability compared with AlgE6.

PubMed: 25266718
DOI: 10.1074/jbc.M114.567008

Experimental method

SOLUTION NMR