FWF - Saccharosephosphorylase - Synthesis of compatible solutes using sucrose phosphorylase

Project: Research project

Description

Compatible solutes constitute a structurally diverse class of small molecules that are synthesized by
microorganisms and different cell types to protect themselves against the effects of various exogenous stresses.
They are often referred to as osmolytes because one of their main roles in cellular physiology is to counteract high
external concentrations of salt or sugars. Organisms dwelling at environmental extremes of temperature, pH or salt
are particularly rich in compatible solutes and produce a range of compounds that appear to be unique to the
lifestyle under extremophilic conditions. Many of these so-called "extremolytes" have a glycosidic structure as in
glucosylglycerol or mannosylglycerate, for example. Typically, they are composed of a sugar residue linked to an
aglycon that is often derived from glycerol but varies in the final structure. Several studies have indicated that these
natural glycosides show an outstanding capability of protecting cells or macromolecular constituents thereof against
denaturation. Various technological applications are immediately implied by these findings. The glycosides could
be used as stabilizers of biopharmaceuticals during downstream processing and formulation, for the conservation of
cells and tissues, and as skin-care reagents and moisturizers in cosmetic products. Despite the clear potential for
commercialization, there are currently no high-yielding and technologically mature processes for the production of
compatible solutes of the glycoside type. Chemical synthesis of compounds having exactly the structure found in
nature is laborious and therefore expensive. The capacity of the biosynthetic pathway is usually too low for
technological exploitation. This project therefore proposes the use of biocatalysis. The extremely efficient
transglycosylation catalyzed by wild-type and engineered forms of sucrose phosphorylase, as already proven in the
enzymatic synthesis of alpha-glucosyl glycerol, will be exploited for the synthesis of the three most prevalent
glycosides known to function as compatible solutes: alpha-glucosyl glycerate; alpha-mannosyl glycerate; alphamannosyl
glyceramide. The enzyme will further offer the possibility to chemically diversify the natural glycosides
into structurally similar compounds that may have different and improved properties. Structure-guided protein
engineering combined with directed evolution of sucrose phosphorylase will be used to obtain catalysts that are
optimized for the particular tasks in synthesis.
StatusFinished
Effective start/end date1/04/0928/02/12