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Functional characterization of three Azotobacter chroococcum alginate-modifying enzymes related to the Azotobacter vinelandii AlgE mannuronan C-5-epimerase family.
- Source :
-
Scientific reports [Sci Rep] 2020 Jul 27; Vol. 10 (1), pp. 12470. Date of Electronic Publication: 2020 Jul 27. - Publication Year :
- 2020
-
Abstract
- Bacterial alginate initially consists of 1-4-linked β-D-mannuronic acid residues (M) which can be later epimerized to α-L-guluronic acid (G). The family of AlgE mannuronan C-5-epimerases from Azotobacter vinelandii has been extensively studied, and three genes putatively encoding AlgE-type epimerases have recently been identified in the genome of Azotobacter chroococcum. The three A. chroococcum genes, here designated AcalgE1, AcalgE2 and AcalgE3, were recombinantly expressed in Escherichia coli and the gene products were partially purified. The catalytic activities of the enzymes were stimulated by the addition of calcium ions in vitro. AcAlgE1 displayed epimerase activity and was able to introduce long G-blocks in the alginate substrate, preferentially by attacking M residues next to pre-existing G residues. AcAlgE2 and AcAlgE3 were found to display lyase activities with a substrate preference toward M-alginate. AcAlgE2 solely accepted M residues in the positions - 1 and + 2 relative to the cleavage site, while AcAlgE3 could accept either M or G residues in these two positions. Both AcAlgE2 and AcAlgE3 were bifunctional and could also catalyze epimerization of M to G. Together, we demonstrate that A. chroococcum encodes three different AlgE-like alginate-modifying enzymes and the biotechnological and biological impact of these findings are discussed.
- Subjects :
- Alginates chemistry
Alginates metabolism
Amino Acid Sequence
Azotobacter chemistry
Azotobacter genetics
Azotobacter vinelandii chemistry
Azotobacter vinelandii genetics
Bacterial Proteins chemistry
Bacterial Proteins genetics
Biocatalysis
Carbohydrate Epimerases chemistry
Carbohydrate Epimerases genetics
Genes, Bacterial
Multigene Family
Sequence Alignment
Substrate Specificity
Azotobacter enzymology
Azotobacter vinelandii enzymology
Bacterial Proteins metabolism
Carbohydrate Epimerases metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 2045-2322
- Volume :
- 10
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Scientific reports
- Publication Type :
- Academic Journal
- Accession number :
- 32719381
- Full Text :
- https://doi.org/10.1038/s41598-020-68789-3