Understanding the influence of glycosylation sites on thermostability of endoglucanases from thermophilic Myceliophthora heterothallica

Abstract

Cellulose from lignocellulose biomass, is the most abundant polysaccharide in the plant kingdom. Cellulose is a linear homopolymer composed of residues of D-glucose linked by ²-1,4 glycosidic bonds. This polymer has attracted attention since its enzymatic hydrolysis results in fermentable sugars which can be directly converted to second-generation bioethanol and cellulases are key enzymes in this process. Several microorganisms were identified as good a producer of cellulases but fungi has been shown an interesting feature because they can secrete some of the cellulases extracellularly. Myceliophthora heterothallica is a thermophilic filamentous fungus and efficient producer of thermotolerant endoglucanases but does not secrete a sufficient amount of endogenous enduglucanases necessary for the structural study. Therefore, we developed heterologous expression systems for two endoglucanases in Pichia pastoris GS115 and Escherichia coli to evaluate expression levels and thermal stabilities of endoglucanases glycosylated and deglycosilated, respectively. In addition, this project proposes to solve the structures of these endoglucanases of Myceliophthora heterothallica providing new information in order to understand the structural basis of thermostability. (AU)