Discovery and Biotechnological Exploitation of Glycoside-Phosphorylases.

Ao Li,Gabrielle Potocki-Veronese,Gianluca Cioci,Simon Ladeveze,Elisabeth Laville,Julien Durand,Mounir Benkoulouche

doi:10.3390/ijms23063043

Abstract

Among carbohydrate active enzymes, glycoside phosphorylases (GPs) are valuable catalysts for white biotechnologies, due to their exquisite capacity to efficiently re-modulate oligo- and poly-saccharides, without the need for costly activated sugars as substrates. The reversibility of the phosphorolysis reaction, indeed, makes them attractive tools for glycodiversification. However, discovery of new GP functions is hindered by the difficulty in identifying them in sequence databases, and, rather, relies on extensive and tedious biochemical characterization studies. Nevertheless, recent advances in automated tools have led to major improvements in GP mining, activity predictions, and functional screening. Implementation of GPs into innovative in vitro and in cellulo bioproduction strategies has also made substantial advances. Herein, we propose to discuss the latest developments in the strategies employed to efficiently discover GPs and make the best use of their exceptional catalytic properties for glycoside bioproduction.

Highlights

As numerous glycosides are used in the food, feed, cosmetics, health, and chemical industries, glycoside-synthesizing enzymes are very interesting tools to produce these compounds in vitro or in cellulo [1,2]
Glycosidic bond formation is mainly performed by glycosyl transferases (GTs), which catalyze the transfer of sugar moieties from an activated donor onto an acceptor molecule [5]
Renewable sourcing of carbon mostly relies on the use of plant polysaccharides, meaning that an increasing number of processes will be dependent on CAZymes

Summary

Introduction

As numerous glycosides are used in the food, feed, cosmetics, health, and chemical industries, glycoside-synthesizing enzymes are very interesting tools to produce these compounds in vitro or in cellulo [1,2]. The role of the nucleophile is played by an activated donor, such as fluorine-containing substrates, providing the energy necessary to cross the barrier for the reaction to occur in the synthesis direction They can, synthesize glycosidic bonds instead of hydrolyzing them. The two reactions of phosphorolysis and reverse phosphorolysis catalyzed by GPs oppose one another, resulting in an equilibrium This is due to the fact that the free energy required for the cleavage of the glycosidic bond is close to the one required for cleavage of the ester linkage in glycosyl phosphates, as demonstrated by a study on cellobiose phosphorylase [22]. In the case of inverting GHs, two catalytic amino acid residues are required: a proton donor that performs the nucleophilic attack on the anomeric carbon, and a catalytic base which activates a water molecule. The oxocarbenium-ion transition state is stabilized by a nucleophile, namely, in this case, a glutamine or an asparagine

Classification and Substrate Specificity

Retaining GPs

Inverting GPs

Tertiary and Quaternary Structures

Biotechnological Applications

Methods for Glycoside Phosphorylase Activity Detection

Chromogenic Assays

Chromatographic and Spectroscopic Methods for Carbohydrate Detection and Characterization

Enzyme Discovery by Functional (Meta)Genomics

Activity-Based Approaches

Sequence-Based Approaches

Findings