Yeast trehalases: Two enzymes,one catalytic mission

BackgroundTrehalose is a non-reducing disaccharide highly conserved throughout evolution. In yeasts, trehalose hydrolysis is confined to the enzyme trehalase, an α-glucosidase specific for trehalose as sole substrate. Two kinds of trehalase activity exist in yeasts: neutral and acid enzymes.Scope of the reviewThis review makes a comparative survey of the main biochemical and genetic parameters, regulatory systems, tridimensional structure and catalytic mechanism of the two yeast trehalases.Major conclusionsThe yeast neutral and acid trehalases display sharp differences in biochemical features (optimum pH, Mr or amino acid sequence) physiological roles, subcellular location (cytosol vs vacuoles or cell wall) and regulatory control (phosphorylation vs catabolite repression). However, their identical specificity for trehalose is based on the presence of an (α/α)₆ toroid folding structure in the active centre and a catalytic mechanism of anomeric inversion.General significanceThis review expands our knowledge of the homology, functional features and catalytic mechanisms of α-glucosidases in yeasts. It provides a further analysis of the correlation between structures and predicted biological roles of macromolecules.