Elucidation of a Unique Pattern and the Role of Carbohydrate Binding Module of an Alginate Lyase.

Fu Hu,Yun Sun,Dengming Ming,Qian Li,Zhong Yao,Heng Yin,Benwei Zhu

doi:10.3390/md18010032

Abstract

Alginate oligosaccharides with different degrees of polymerization (DPs) possess diverse physiological activities. Therefore, in recent years, increasing attention has been drawn to the use of enzymes for the preparation of alginate oligosaccharides for food and industrial applications. Previously, we identified and characterized a novel bifunctional alginate lyase Aly7A, which can specifically release trisaccharide from three different substrate types with a unique degradation pattern. Herein, we investigated its degradation pattern by modular truncation and molecular docking. The results suggested that Aly7A adopted a unique action mode towards different substrates with the substrate chain sliding into the binding pocket of the catalytic domain to position the next trisaccharide for cleavage. Deletion of the Aly7A carbohydrate binding module (CBM) domain resulted in a complex distribution of degradation products and no preference for trisaccharide formation, indicating that the CBM may act as a “controller” during the trisaccharide release process. This study further testifies CBM as a regulator of product distribution and provides new insights into well-defined generation of alginate oligosaccharides with associated CBMs.

Highlights

Alginate is a linear anionic polysaccharide that is the major component of the cell walls of brown algae
Alginate oligosaccharides are depolymerized degradation products of alginate that are produced by physicochemical methods or through the action of alginate lyases
“QIH” were conserved in these alginate lyases, which were necessary for catalysis and binding of substrates [40]

Summary

Introduction

Alginate is a linear anionic polysaccharide that is the major component of the cell walls of brown algae It is composed of the monomeric units 1,4-linked β-d-mannuronate (M) and its C5 epimer, α-l-guluronate (G) [1]. Alginate oligosaccharides are widely utilized in the food, agricultural, and pharmaceutical industries as additives and therapeutic agents [3,4,5,6,7,8]. They are used to lower blood sugar and lipids, and have shown considerable potential as a treatment for cystic fibrosis [9,10]. It is almost impossible to scale up the production of alginate oligosaccharides

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Conclusion