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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
11
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pubmed:dateCreated |
2006-3-13
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pubmed:databankReference |
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pubmed:abstractText |
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.
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Alginates,
http://linkedlifedata.com/resource/pubmed/chemical/Amino Acids,
http://linkedlifedata.com/resource/pubmed/chemical/Calcium,
http://linkedlifedata.com/resource/pubmed/chemical/Carbohydrate Epimerases,
http://linkedlifedata.com/resource/pubmed/chemical/Hexuronic Acids,
http://linkedlifedata.com/resource/pubmed/chemical/Ions,
http://linkedlifedata.com/resource/pubmed/chemical/Polymers,
http://linkedlifedata.com/resource/pubmed/chemical/Thulium,
http://linkedlifedata.com/resource/pubmed/chemical/guluronic acid,
http://linkedlifedata.com/resource/pubmed/chemical/mannuronan c-5-epimerase,
http://linkedlifedata.com/resource/pubmed/chemical/mannuronic acid
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pubmed:status |
MEDLINE
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pubmed:month |
Mar
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pubmed:issn |
0021-9258
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
17
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pubmed:volume |
281
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
7350-6
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:16407237-Alginates,
pubmed-meshheading:16407237-Amino Acid Sequence,
pubmed-meshheading:16407237-Amino Acids,
pubmed-meshheading:16407237-Azotobacter vinelandii,
pubmed-meshheading:16407237-Calcium,
pubmed-meshheading:16407237-Carbohydrate Epimerases,
pubmed-meshheading:16407237-Hexuronic Acids,
pubmed-meshheading:16407237-Ions,
pubmed-meshheading:16407237-Magnetic Resonance Spectroscopy,
pubmed-meshheading:16407237-Models, Molecular,
pubmed-meshheading:16407237-Models, Statistical,
pubmed-meshheading:16407237-Molecular Conformation,
pubmed-meshheading:16407237-Molecular Sequence Data,
pubmed-meshheading:16407237-Polymers,
pubmed-meshheading:16407237-Protein Binding,
pubmed-meshheading:16407237-Protein Conformation,
pubmed-meshheading:16407237-Protein Folding,
pubmed-meshheading:16407237-Protein Structure, Secondary,
pubmed-meshheading:16407237-Protein Structure, Tertiary,
pubmed-meshheading:16407237-Thulium
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pubmed:year |
2006
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pubmed:articleTitle |
NMR structure of the R-module: a parallel beta-roll subunit from an Azotobacter vinelandii mannuronan C-5 epimerase.
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pubmed:affiliation |
Department of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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