|The sulphated-galactan hydrolases, agarases and carrageenases: structural biology and molecular evolution|
Barbeyron, T.; Flament, D.; Michel, G.; Potin, Ph.; Kloareg, B. (2001). The sulphated-galactan hydrolases, agarases and carrageenases: structural biology and molecular evolution. Cah. Biol. Mar. 42(1-2): 169-183
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723, more
|Also published as |
- Barbeyron, T.; Flament, D.; Michel, G.; Potin, Ph.; Kloareg, B. (2001). The sulphated-galactan hydrolases, agarases and carrageenases: structural biology and molecular evolution, in: Proceedings of the International Workshop "Current approaches in basic and applied phycology". Cahiers de Biologie Marine, 42(1-2): pp. 169-183, more
|Authors|| || Top |
- Barbeyron, T.
- Flament, D.
- Michel, G.
The carrageenans and agars are major cell-wall polysaccharides from red algae. These sulphated galactans are degraded by enzymes, called carrageenases and agarases that display strict substrate specifities and recognize the pattern of galactan sulphation. From a set of various marine bacteria enzymes, we have investigated the influence of ester-sulphate groups, of D/L isomery and of linkage anomery on the structure-function relationships of the specific galactan hydrolases that degrade sulphated polysaccharides. With this aim, we have cloned a representative set of sulphated-galactan hydrolase genes. The sequence analysis methods indicate that the beta-agarases and kappa- carrageenases display secondary structure similarities with members of family 16 of glycoside hydrolases. In contrast, the L-carrageenases have no structural relationships with the family-16 beta-agarases and kappa-carrageenases and they constitute a novel structural family of glycan hydrolases. As a preliminary step towards the functional analysis of these two structural families, we have overexpressed the L- and kappa-carrageenase genes in Escherichia coli and crystals from these enzymes have been obtained. Finally, an alpha-agarase, the only one galactanase known to cleave the alpha-1,3 linkage in agarose has no similarity with other glycoside hydrolases or proteins and display some interesting characteristics. To date, this enzyme is an unclassified glycoside hydrolase.