EC Number   |
General Information |
Reference |
|---|
    5.1.3.37 | more |
alginate epimerases consist of catalytic and noncatalytic domains. The noncatalytic domains of AlgE4 and AlgE6 possess different alginate binding behavior despite highly similar structures. Noncatalytic subunits of AlgE6 and AlgE4 influence the product specificity of the catalytic domain |
748180 |
| 5.1.3.37 | physiological function |
alginate is produced as poly-M and then certain M residues are converted to G by epimerases acting on the polymer level. The alginate-producing bacterium Azotobacter vinelandii has one periplasmic epimerase, which incorporates single G residues into the alginate during secretion of the polymer. In addition, Azotobacter vinelandii produces seven extracellular C-5 alginate epimerases called AlgE1-7. Each of the epimerases convert mannuronic acid to guluronic acid in different patterns. The secreted and calcium-dependent mannuronan C-5 epimerases in Azotobacter vinelandii are responsible for epimerization of beta-D-mannuronic acid (M) to alpha-L-guluronic acid (G) in alginate polymers |
748180 |
| 5.1.3.37 | physiological function |
alginate is produced as poly-M and then certain M residues are converted to G by epimerases acting on the polymer level. The alginate-producing bacterium Azotobacter vinelandii has one periplasmic epimerase, which incorporates single G residues into the alginate during secretion of the polymer. In addition, Azotobacter vinelandii produces seven extracellular C-5 alginate epimerases called AlgE1-7. Each of the epimerases converts mannuronic acid to guluronic acid in different patterns. The secreted and calcium-dependent mannuronan C-5 epimerases in Azotobacter vinelandii are responsible for epimerization of beta-D-mannuronic acid (M) to alpha-L-guluronic acid (G) in alginate polymers |
748180 |
| 5.1.3.37 | physiological function |
an isoform algG deletion mutant produces predominantly an unsaturated disaccharide containing a 4-deoxy-L-erythro-hex-4-enepyranosyluronate residue at the nonreducing end and a mannuronic acid residue at the reducing end. The production of this dimer is the result of the activity of an alginate lyase, AlgL, whose in vivo activity is much more limited in the presence of AlgG. A strain expressing both an epimerase-defective and a wild-type epimerase produces two types of alginate molecules: one class being pure mannuronan and the other having the wild-type content of guluronic acid residues. This formation of two distinct classes of polymers in a genetically pure cell line can be explained if AlgG is part of a periplasmic protein complex |
734063 |
| 5.1.3.37 | metabolism |
biosynthetic pathway of alginate and the alginate structure involving the enzyme, overview |
746698 |
| 5.1.3.37 | evolution |
Ectocarpus contains a multigenic family of putative ManC5-Es. The genome sequence of Ectocarpus offers the opportunity to have access to a higher number of genes, and potentially proteins, 31 putative ManC5-E genes are analyzed. The ManC5-E family includes genes that are differentially regulated during the life cycle of Ectocarpus |
747915 |
| 5.1.3.37 | physiological function |
generation of a strain in which all the algE genes are inactivated by deletion (algE1-4 and algE1-7) or interruption (algE5). The shake flask-grown mutant strain produces a polymer containing less than 2% G (with periplasmic isoform algG still active), while wild-type alginates contain 25% G. Addition of proteases to growth medium results in a strong increase in the chain lengths of the alginates produced. The mutant strain is unable to form functional cysts. Single algE gene inactivations, with the exception of algE3, has no detected effect on cell growth, morphology or alginate structure |
733738 |
| 5.1.3.37 | physiological function |
generation of a strain in which all the algE genes are inactivated by deletion (algE1-4 and algE6-7) or interruption (algE5). The shake flask-grown mutant strain produces a polymer containing less than 2% G (with periplasmic isoform algG still active), while wild-type alginates contain 25% G. Addition of proteases to growth medium results in a strong increase in the chain lengths of the alginates produced. The mutant strain is unable to form functional cysts. single isoform AlgE3 insertion mutants produce alginates with a G content as low as 8%, and contain almost no GG diads |
733738 |
| 5.1.3.37 | physiological function |
in brown algae, the M/G ratio and the composition of blocks consisting of these residues varies based on several factors, including species, portion (blade, stipe, and rhizoid), season, growth conditions, and habitat. Analysis of expression and enzymatic characterization of brown algal MC5E(s) |
746698 |
| 5.1.3.37 | physiological function |
mannuronan C5-epimerases (ManC5-Es) catalyze in brown algae the remodeling of alginate, a major cell-wall component which is involved in many biological functions in these organisms. ManC5-Es are present as large multigenic families in brown algae, likely indicating functional specificities and specializations. ManC5-Es control the distribution pattern of (1-4)-linked beta-D-mannuronic acid (M) and alpha-L-guluronic acid (G) residues in alginates, giving rise to widely different polysaccharide compositions and sequences, depending on tissue, season, age, or algal species. Alginate in brown algae is first formed as a polysaccharide chain containing mannuronic acid residues only. These are subsequently transformed by the ManC5-E into guluronic acid residues, generating distinct patterns arranged in regions of MM-, GG- and MG-blocks. Patterns containing large stretches of adjacent guluronic acid residues (GG-blocks) form structured interchain associations in the presence of Ca2+ ions. These interchain junctions have the socalled egg-box conformation and are responsible for the gelling properties of alginate and cell-wall strengthening |
747915 |
