Gluten-Degrading Proteases in Wheat Infected by Fusarium graminearumProtease Identification and Effects on Gluten and Dough Properties

Recently, we have observed a relationship
between poor breadmaking
quality and protease activities related to fungal infection. This
study aims to identify potential gluten-degrading proteases secreted
by fungi and to analyze effects of these proteases on rheological
properties of dough and gluten. Fusarium graminearum-infected grain was used as a model system. Zymography showed that
serine-type proteases secreted by F. graminearum degrade gluten proteins. Zymography followed by liquid chromatography–mass
spectrometry (MS)/MS analysis predicted one serine carboxypeptidase
and seven serine endo-peptidases to be candidate fungal proteases
involved in gluten degradation. Effects of fungal proteases on the
time-dependent rheological properties of dough and gluten were analyzed
by small amplitude oscillatory shear rheology and large deformation
extensional rheology. Our results indicate that fungal proteases degrade
gluten proteins not only in the grain itself, but also during dough
preparation and resting. Our study gives new insights into fungal
proteases and their potential role in weakening of gluten.