Cloning, expression, and molecular dynamics simulations of a xylosidase obtained from Thermomyces lanuginosus

The aim of this study was to clone, express, and characterize a -xylosidase (Tlxyn1) from the thermophilic fungus Thermomyces lanuginosus SSBP in Pichia pastoris GS115 as well as analyze optimal activity and stability using computational and experimental methods. The enzyme was constitutively expressed using the GAP promoter and secreted into the medium due to the alpha-mating factor secretion signal present on the expression vector pBGPI. The 1276bp gene consists of an open reading frame that does not contain introns. A 12% SDS-PAGE gel revealed a major protein band at an estimated molecular mass of 50kDa which corresponded to zymogram analysis. The three-dimensional structure of -xylosidase was predicted, and molecular dynamics simulations at different ranges of temperature and pH were performed in order to predict optimal activity and folding energy. The results suggested a strong conformational temperature and pH dependence. The recombinant enzyme exhibited optimal activity at pH 7 and 50 degrees C and retained 80% activity at 50 degrees C, pH 7 for about 45min. This is the first report of the cloning, functional expression, and simulations study of a -xylosidase from Thermomyces species in a fungal host.