Trehalose degradation, low osmolarity (Saccharomyces cerevisiae)

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Trehalose is a storage carbohydrate that can either be synthesized or obtained from the external environment. To be utilized as a carbon source, trehalase (EC:3.2.1.28) must convert trehalose and water into two molecules of glucose [ Francois01 ]. S. cerevisiae has two trehalase enzymes, one is an acid trehalase encoded by ATH1 [ Alizadeh96 ] and the other is a neutral trehalase encoded by NTH1 [ Kopp93 ]. The name "acid" or "neutral" are based on the optimal pH of each enzyme (pH 4.5-5.0 and pH 6.8-7.0, respectively) [ Francois01 ]. Each trehalase enzyme is active in a different subcellular location. Nth1p occurs as homodimer that is located in the cytoplasm, and is required for the hydrolysis of intracellular trehalose [ Jules04 ]. Intracellular trehalose either results from trehalose biosynthesis, or to a lesser degree from uptake of trehalose from the environment via the Mal11p transporter. Ath1p was originally predicted to be a vacuolar protein, but has been experimentally shown to mainly localize in the periplasmic space, with a small fraction also occurring in the cell wall [ Jules04 ]. Extracellular trehalose is hydrolysed into 2 glucose molecules by Ath1p [ Jules04 ].

GenMAPP remarks 

Based on http://pathway.yeastgenome.org/biocyc/